# Messages

## Create a Message

`beta.messages.create(**kwargs) -> BetaMessage`

**post** `/v1/messages`

Send a structured list of input messages with text and/or image content, and the model will generate the next message in the conversation.

The Messages API can be used for either single queries or stateless multi-turn conversations.

Learn more about the Messages API in our [user guide](https://docs.claude.com/en/docs/initial-setup)

### Parameters

- `max_tokens: Integer`

  The maximum number of tokens to generate before stopping.

  Note that our models may stop _before_ reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.

  Set to `0` to populate the [prompt cache](https://docs.claude.com/en/docs/build-with-claude/prompt-caching#pre-warming-the-cache) without generating a response.

  Different models have different maximum values for this parameter.  See [models](https://docs.claude.com/en/docs/models-overview) for details.

- `messages: Array[BetaMessageParam]`

  Input messages.

  Our models are trained to operate on alternating `user` and `assistant` conversational turns. When creating a new `Message`, you specify the prior conversational turns with the `messages` parameter, and the model then generates the next `Message` in the conversation. Consecutive `user` or `assistant` turns in your request will be combined into a single turn.

  Each input message must be an object with a `role` and `content`. You can specify a single `user`-role message, or you can include multiple `user` and `assistant` messages.

  If the final message uses the `assistant` role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

  Example with a single `user` message:

  ```json
  [{"role": "user", "content": "Hello, Claude"}]
  ```

  Example with multiple conversational turns:

  ```json
  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]
  ```

  Example with a partially-filled response from Claude:

  ```json
  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]
  ```

  Each input message `content` may be either a single `string` or an array of content blocks, where each block has a specific `type`. Using a `string` for `content` is shorthand for an array of one content block of type `"text"`. The following input messages are equivalent:

  ```json
  {"role": "user", "content": "Hello, Claude"}
  ```

  ```json
  {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}
  ```

  See [input examples](https://docs.claude.com/en/api/messages-examples).

  Note that if you want to include a [system prompt](https://docs.claude.com/en/docs/system-prompts), you can use the top-level `system` parameter — there is no `"system"` role for input messages in the Messages API.

  There is a limit of 100,000 messages in a single request.

  - `content: String | Array[BetaContentBlockParam]`

    - `String = String`

    - `UnionMember1 = Array[BetaContentBlockParam]`

      - `class BetaTextBlockParam`

        - `text: String`

        - `type: :text`

          - `:text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

          - `type: :ephemeral`

            - `:ephemeral`

          - `ttl: :"5m" | :"1h"`

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            - `5m`: 5 minutes
            - `1h`: 1 hour

            Defaults to `5m`.

            - `:"5m"`

            - `:"1h"`

        - `citations: Array[BetaTextCitationParam]`

          - `class BetaCitationCharLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationWebSearchResultLocationParam`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

      - `class BetaImageBlockParam`

        - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

          - `class BetaBase64ImageSource`

            - `data: String`

            - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

              - `:"image/jpeg"`

              - `:"image/png"`

              - `:"image/gif"`

              - `:"image/webp"`

            - `type: :base64`

              - `:base64`

          - `class BetaURLImageSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileImageSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :image`

          - `:image`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestDocumentBlock`

        - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

          - `class BetaContentBlockSource`

            - `content: String | Array[BetaContentBlockSourceContent]`

              - `String = String`

              - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                - `class BetaTextBlockParam`

                - `class BetaImageBlockParam`

            - `type: :content`

              - `:content`

          - `class BetaURLPDFSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileDocumentSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :document`

          - `:document`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          - `enabled: bool`

        - `context: String`

        - `title: String`

      - `class BetaSearchResultBlockParam`

        - `content: Array[BetaTextBlockParam]`

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `source: String`

        - `title: String`

        - `type: :search_result`

          - `:search_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

      - `class BetaThinkingBlockParam`

        - `signature: String`

        - `thinking: String`

        - `type: :thinking`

          - `:thinking`

      - `class BetaRedactedThinkingBlockParam`

        - `data: String`

        - `type: :redacted_thinking`

          - `:redacted_thinking`

      - `class BetaToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `type: :tool_use`

          - `:tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

            - `type: :direct`

              - `:direct`

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

            - `tool_id: String`

            - `type: :code_execution_20250825`

              - `:code_execution_20250825`

          - `class BetaServerToolCaller20260120`

            - `tool_id: String`

            - `type: :code_execution_20260120`

              - `:code_execution_20260120`

      - `class BetaToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :tool_result`

          - `:tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

          - `String = String`

          - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

            - `class BetaTextBlockParam`

            - `class BetaImageBlockParam`

            - `class BetaSearchResultBlockParam`

            - `class BetaRequestDocumentBlock`

            - `class BetaToolReferenceBlockParam`

              Tool reference block that can be included in tool_result content.

              - `tool_name: String`

              - `type: :tool_reference`

                - `:tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

        - `is_error: bool`

      - `class BetaServerToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: :advisor | :web_search | :web_fetch | 5 more`

          - `:advisor`

          - `:web_search`

          - `:web_fetch`

          - `:code_execution`

          - `:bash_code_execution`

          - `:text_editor_code_execution`

          - `:tool_search_tool_regex`

          - `:tool_search_tool_bm25`

        - `type: :server_tool_use`

          - `:server_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebSearchToolResultBlockParam`

        - `content: BetaWebSearchToolResultBlockParamContent`

          - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

            - `encrypted_content: String`

            - `title: String`

            - `type: :web_search_result`

              - `:web_search_result`

            - `url: String`

            - `page_age: String`

          - `class BetaWebSearchToolRequestError`

            - `error_code: BetaWebSearchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:max_uses_exceeded`

              - `:too_many_requests`

              - `:query_too_long`

              - `:request_too_large`

            - `type: :web_search_tool_result_error`

              - `:web_search_tool_result_error`

        - `tool_use_id: String`

        - `type: :web_search_tool_result`

          - `:web_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebFetchToolResultBlockParam`

        - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

          - `class BetaWebFetchToolResultErrorBlockParam`

            - `error_code: BetaWebFetchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:url_too_long`

              - `:url_not_allowed`

              - `:url_not_in_prior_context`

              - `:url_not_accessible`

              - `:unsupported_content_type`

              - `:too_many_requests`

              - `:max_uses_exceeded`

              - `:unavailable`

            - `type: :web_fetch_tool_result_error`

              - `:web_fetch_tool_result_error`

          - `class BetaWebFetchBlockParam`

            - `content: BetaRequestDocumentBlock`

            - `type: :web_fetch_result`

              - `:web_fetch_result`

            - `url: String`

              Fetched content URL

            - `retrieved_at: String`

              ISO 8601 timestamp when the content was retrieved

        - `tool_use_id: String`

        - `type: :web_fetch_tool_result`

          - `:web_fetch_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaAdvisorToolResultBlockParam`

        - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

          - `class BetaAdvisorToolResultErrorParam`

            - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

              - `:max_uses_exceeded`

              - `:prompt_too_long`

              - `:too_many_requests`

              - `:overloaded`

              - `:unavailable`

              - `:execution_time_exceeded`

              - `:model_not_found`

            - `type: :advisor_tool_result_error`

              - `:advisor_tool_result_error`

          - `class BetaAdvisorResultBlockParam`

            - `text: String`

            - `type: :advisor_result`

              - `:advisor_result`

            - `stop_reason: String`

          - `class BetaAdvisorRedactedResultBlockParam`

            - `encrypted_content: String`

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            - `type: :advisor_redacted_result`

              - `:advisor_redacted_result`

            - `stop_reason: String`

        - `tool_use_id: String`

        - `type: :advisor_tool_result`

          - `:advisor_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCodeExecutionToolResultBlockParam`

        - `content: BetaCodeExecutionToolResultBlockParamContent`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `class BetaCodeExecutionToolResultErrorParam`

            - `error_code: BetaCodeExecutionToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :code_execution_tool_result_error`

              - `:code_execution_tool_result_error`

          - `class BetaCodeExecutionResultBlockParam`

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

                - `:code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :code_execution_result`

              - `:code_execution_result`

          - `class BetaEncryptedCodeExecutionResultBlockParam`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

            - `encrypted_stdout: String`

            - `return_code: Integer`

            - `stderr: String`

            - `type: :encrypted_code_execution_result`

              - `:encrypted_code_execution_result`

        - `tool_use_id: String`

        - `type: :code_execution_tool_result`

          - `:code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaBashCodeExecutionToolResultBlockParam`

        - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

          - `class BetaBashCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:output_file_too_large`

            - `type: :bash_code_execution_tool_result_error`

              - `:bash_code_execution_tool_result_error`

          - `class BetaBashCodeExecutionResultBlockParam`

            - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :bash_code_execution_output`

                - `:bash_code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :bash_code_execution_result`

              - `:bash_code_execution_result`

        - `tool_use_id: String`

        - `type: :bash_code_execution_tool_result`

          - `:bash_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaTextEditorCodeExecutionToolResultBlockParam`

        - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

          - `class BetaTextEditorCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:file_not_found`

            - `type: :text_editor_code_execution_tool_result_error`

              - `:text_editor_code_execution_tool_result_error`

            - `error_message: String`

          - `class BetaTextEditorCodeExecutionViewResultBlockParam`

            - `content: String`

            - `file_type: :text | :image | :pdf`

              - `:text`

              - `:image`

              - `:pdf`

            - `type: :text_editor_code_execution_view_result`

              - `:text_editor_code_execution_view_result`

            - `num_lines: Integer`

            - `start_line: Integer`

            - `total_lines: Integer`

          - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

            - `is_file_update: bool`

            - `type: :text_editor_code_execution_create_result`

              - `:text_editor_code_execution_create_result`

          - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

            - `type: :text_editor_code_execution_str_replace_result`

              - `:text_editor_code_execution_str_replace_result`

            - `lines: Array[String]`

            - `new_lines: Integer`

            - `new_start: Integer`

            - `old_lines: Integer`

            - `old_start: Integer`

        - `tool_use_id: String`

        - `type: :text_editor_code_execution_tool_result`

          - `:text_editor_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaToolSearchToolResultBlockParam`

        - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

          - `class BetaToolSearchToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :tool_search_tool_result_error`

              - `:tool_search_tool_result_error`

            - `error_message: String`

          - `class BetaToolSearchToolSearchResultBlockParam`

            - `tool_references: Array[BetaToolReferenceBlockParam]`

              - `tool_name: String`

              - `type: :tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

            - `type: :tool_search_tool_search_result`

              - `:tool_search_tool_search_result`

        - `tool_use_id: String`

        - `type: :tool_search_tool_result`

          - `:tool_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaMCPToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `server_name: String`

          The name of the MCP server

        - `type: :mcp_tool_use`

          - `:mcp_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestMCPToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :mcp_tool_result`

          - `:mcp_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam]`

          - `String = String`

          - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

            - `text: String`

            - `type: :text`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `citations: Array[BetaTextCitationParam]`

        - `is_error: bool`

      - `class BetaContainerUploadBlockParam`

        A content block that represents a file to be uploaded to the container
        Files uploaded via this block will be available in the container's input directory.

        - `file_id: String`

        - `type: :container_upload`

          - `:container_upload`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCompactionBlockParam`

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests
        to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server
        treats these as no-ops. Empty string content is not allowed.

        - `type: :compaction`

          - `:compaction`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String`

          Summary of previously compacted content, or null if compaction failed

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

      - `class BetaMidConversationSystemBlockParam`

        System instructions that appear mid-conversation.

        Use this block to provide or update system-level instructions at a specific
        point in the conversation, rather than only via the top-level `system` parameter.

        - `content: Array[BetaTextBlockParam]`

          System instruction text blocks.

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `type: :mid_conv_system`

          - `:mid_conv_system`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaFallbackBlockParam`

        A `fallback` block echoed back from a prior response.

        Accepted in `messages[].content` and never rendered into the prompt,
        not validated against the request's `fallbacks` chain or top-level
        `model`, and stripped before the sticky-routing cache key is computed.

        Callers should echo the assistant turn verbatim — block included. The
        block's position is load-bearing for thinking verification: the thinking
        runs on either side of a fallback hop carry independently-rooted
        verification hash chains, and this block is the only record of where one
        chain ends and the next begins. When thinking runs flank the boundary,
        omitting the block merges the runs into one contiguous span whose hashes
        cannot verify (the request is rejected), and moving it into the middle of
        a single run splits that run's chain and is likewise rejected; between
        non-thinking blocks the block's placement has no verification effect.

        - `from: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `:"claude-fable-5"`

                Next generation of intelligence for the hardest knowledge work and coding problems

              - `:"claude-mythos-5"`

                Most capable model for cybersecurity and biology research

              - `:"claude-opus-4-8"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-opus-4-7"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-mythos-preview"`

                New class of intelligence, strongest in coding and cybersecurity

              - `:"claude-opus-4-6"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-sonnet-4-6"`

                Best combination of speed and intelligence

              - `:"claude-haiku-4-5"`

                Fastest model with near-frontier intelligence

              - `:"claude-haiku-4-5-20251001"`

                Fastest model with near-frontier intelligence

              - `:"claude-opus-4-5"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-opus-4-5-20251101"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-sonnet-4-5"`

                High-performance model for agents and coding

              - `:"claude-sonnet-4-5-20250929"`

                High-performance model for agents and coding

              - `:"claude-opus-4-1"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-1-20250805"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-0"`

                Powerful model for complex tasks

              - `:"claude-opus-4-20250514"`

                Powerful model for complex tasks

              - `:"claude-sonnet-4-0"`

                High-performance model with extended thinking

              - `:"claude-sonnet-4-20250514"`

                High-performance model with extended thinking

              - `:"claude-3-haiku-20240307"`

                Fast and cost-effective model

            - `String = String`

        - `to: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

        - `type: :fallback`

          - `:fallback`

  - `role: :user | :assistant | :system`

    - `:user`

    - `:assistant`

    - `:system`

- `model: Model`

  The model that will complete your prompt.

  See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

- `cache_control: BetaCacheControlEphemeral`

  Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

- `container: BetaContainerParams | String`

  Container identifier for reuse across requests.

  - `class BetaContainerParams`

    Container parameters with skills to be loaded.

    - `id: String`

      Container id

    - `skills: Array[BetaSkillParams]`

      List of skills to load in the container

      - `skill_id: String`

        Skill ID

      - `type: :anthropic | :custom`

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        - `:anthropic`

        - `:custom`

      - `version: String`

        Skill version or 'latest' for most recent version

  - `String = String`

- `context_management: BetaContextManagementConfig`

  Context management configuration.

  This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

  - `edits: Array[BetaClearToolUses20250919Edit | BetaClearThinking20251015Edit | BetaCompact20260112Edit]`

    List of context management edits to apply

    - `class BetaClearToolUses20250919Edit`

      - `type: :clear_tool_uses_20250919`

        - `:clear_tool_uses_20250919`

      - `clear_at_least: BetaInputTokensClearAtLeast`

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        - `type: :input_tokens`

          - `:input_tokens`

        - `value: Integer`

      - `clear_tool_inputs: bool | Array[String]`

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        - `UnionMember0 = bool`

        - `UnionMember1 = Array[String]`

      - `exclude_tools: Array[String]`

        Tool names whose uses are preserved from clearing

      - `keep: BetaToolUsesKeep`

        Number of tool uses to retain in the conversation

        - `type: :tool_uses`

          - `:tool_uses`

        - `value: Integer`

      - `trigger: BetaInputTokensTrigger | BetaToolUsesTrigger`

        Condition that triggers the context management strategy

        - `class BetaInputTokensTrigger`

          - `type: :input_tokens`

            - `:input_tokens`

          - `value: Integer`

        - `class BetaToolUsesTrigger`

          - `type: :tool_uses`

            - `:tool_uses`

          - `value: Integer`

    - `class BetaClearThinking20251015Edit`

      - `type: :clear_thinking_20251015`

        - `:clear_thinking_20251015`

      - `keep: BetaThinkingTurns | BetaAllThinkingTurns | :all`

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        - `class BetaThinkingTurns`

          - `type: :thinking_turns`

            - `:thinking_turns`

          - `value: Integer`

        - `class BetaAllThinkingTurns`

          - `type: :all`

            - `:all`

        - `Keep = :all`

          - `:all`

    - `class BetaCompact20260112Edit`

      Automatically compact older context when reaching the configured trigger threshold.

      - `type: :compact_20260112`

        - `:compact_20260112`

      - `instructions: String`

        Additional instructions for summarization.

      - `pause_after_compaction: bool`

        Whether to pause after compaction and return the compaction block to the user.

      - `trigger: BetaInputTokensTrigger`

        When to trigger compaction. Defaults to 150000 input tokens.

- `diagnostics: BetaDiagnosticsParam`

  Request-level diagnostics. Currently carries the previous response
  id for prompt-cache divergence reporting.

  - `previous_message_id: String`

    The `id` (`msg_...`) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns `diagnostics.cache_miss_reason` when the prompt-cache prefix could not be reused. Pass `null` on the first turn to opt in without a prior message to compare.

- `fallback_credit_token: String`

  The `fallback_credit_token` from a prior refusal's `stop_details`.

  When a preceding request was refused and returned a `fallback_credit_token`,
  pass that code here on the retry to have the retry's cache-creation tokens
  for the prefix that was warm on the refused model billed at the cache-read
  rate. Must be redeemed by the same organization and workspace, with the same
  request body (optionally extended by one appended `assistant` message whose
  content is the partial text — with any trailing whitespace stripped from
  the final text block — and paired server-tool blocks streamed before the
  refusal; the appended-assistant form is not available for requests with
  `output_format` set or forced `tool_choice`), on an eligible fallback
  model, on the same platform,
  and within 5 minutes of the refusal; a mismatch is a 400. A token minted
  mid-server-tool-loop whose partial content was continuable may only be
  redeemed with the appended-assistant form — if an exact-body retry is
  rejected with a 400 saying the token must be redeemed by continuing the
  partial response, retry with the appended-assistant form instead.

  When the appended-assistant form is used on a model that otherwise disallows
  assistant-turn prefill, this token also authorizes that one prefill.

- `fallbacks: Array[BetaFallbackParam]`

  Opt-in server-side retry on one or more substitute models when the requested model declines for policy reasons. Tried in order: if the first entry also declines, the second is tried, and so on.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

  - `max_tokens: Integer`

  - `output_config: BetaOutputConfig`

    - `effort: :low | :medium | :high | 2 more`

      All possible effort levels.

      - `:low`

      - `:medium`

      - `:high`

      - `:xhigh`

      - `:max`

    - `format_: BetaJSONOutputFormat`

      A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

      - `schema: Hash[Symbol, untyped]`

        The JSON schema of the format

      - `type: :json_schema`

        - `:json_schema`

    - `task_budget: BetaTokenTaskBudget`

      User-configurable total token budget across contexts.

      - `total: Integer`

        Total token budget across all contexts in the session.

      - `type: :tokens`

        The budget type. Currently only 'tokens' is supported.

        - `:tokens`

      - `remaining: Integer`

        Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

  - `speed: :standard | :fast`

    - `:standard`

    - `:fast`

  - `thinking: BetaThinkingConfigEnabled | BetaThinkingConfigDisabled | BetaThinkingConfigAdaptive`

    - `class BetaThinkingConfigEnabled`

      - `budget_tokens: Integer`

        Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

        Must be ≥1024 and less than `max_tokens`.

        See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

      - `type: :enabled`

        - `:enabled`

      - `display_: :summarized | :omitted`

        Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

        - `:summarized`

        - `:omitted`

    - `class BetaThinkingConfigDisabled`

      - `type: :disabled`

        - `:disabled`

    - `class BetaThinkingConfigAdaptive`

      - `type: :adaptive`

        - `:adaptive`

      - `display_: :summarized | :omitted`

        Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

        - `:summarized`

        - `:omitted`

- `inference_geo: String`

  Specifies the geographic region for inference processing. If not specified, the workspace's `default_inference_geo` is used.

- `mcp_servers: Array[BetaRequestMCPServerURLDefinition]`

  MCP servers to be utilized in this request

  - `name: String`

  - `type: :url`

    - `:url`

  - `url: String`

  - `authorization_token: String`

  - `tool_configuration: BetaRequestMCPServerToolConfiguration`

    - `allowed_tools: Array[String]`

    - `enabled: bool`

- `metadata: BetaMetadata`

  An object describing metadata about the request.

  - `user_id: String`

    An external identifier for the user who is associated with the request.

    This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

- `output_config: BetaOutputConfig`

  Configuration options for the model's output, such as the output format.

- `output_format: BetaJSONOutputFormat`

  Deprecated: Use `output_config.format` instead. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

  A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

- `service_tier: :auto | :standard_only`

  Determines whether to use priority capacity (if available) or standard capacity for this request.

  Anthropic offers different levels of service for your API requests. See [service-tiers](https://docs.claude.com/en/api/service-tiers) for details.

  - `:auto`

  - `:standard_only`

- `speed: :standard | :fast`

  The inference speed mode for this request. `"fast"` enables high output-tokens-per-second inference.

  - `:standard`

  - `:fast`

- `stop_sequences: Array[String]`

  Custom text sequences that will cause the model to stop generating.

  Our models will normally stop when they have naturally completed their turn, which will result in a response `stop_reason` of `"end_turn"`.

  If you want the model to stop generating when it encounters custom strings of text, you can use the `stop_sequences` parameter. If the model encounters one of the custom sequences, the response `stop_reason` value will be `"stop_sequence"` and the response `stop_sequence` value will contain the matched stop sequence.

- `stream: bool`

  Whether to incrementally stream the response using server-sent events.

  See [streaming](https://docs.claude.com/en/api/messages-streaming) for details.

- `system_: String | Array[BetaTextBlockParam]`

  System prompt.

  A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our [guide to system prompts](https://docs.claude.com/en/docs/system-prompts).

  - `String = String`

  - `UnionMember1 = Array[BetaTextBlockParam]`

    - `text: String`

    - `type: :text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: Array[BetaTextCitationParam]`

- `temperature: Float`

  Amount of randomness injected into the response.

  Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0` for analytical / multiple choice, and closer to `1.0` for creative and generative tasks.

  Note that even with `temperature` of `0.0`, the results will not be fully deterministic.

- `thinking: BetaThinkingConfigParam`

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include `thinking` content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your `max_tokens` limit.

  See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

  - `class BetaThinkingConfigEnabled`

  - `class BetaThinkingConfigDisabled`

  - `class BetaThinkingConfigAdaptive`

- `tool_choice: BetaToolChoice`

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  - `class BetaToolChoiceAuto`

    The model will automatically decide whether to use tools.

    - `type: :auto`

      - `:auto`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output at most one tool use.

  - `class BetaToolChoiceAny`

    The model will use any available tools.

    - `type: :any`

      - `:any`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceTool`

    The model will use the specified tool with `tool_choice.name`.

    - `name: String`

      The name of the tool to use.

    - `type: :tool`

      - `:tool`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceNone`

    The model will not be allowed to use tools.

    - `type: :none`

      - `:none`

- `tools: Array[BetaToolUnion]`

  Definitions of tools that the model may use.

  If you include `tools` in your API request, the model may return `tool_use` content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using `tool_result` content blocks.

  There are two types of tools: **client tools** and **server tools**. The behavior described below applies to client tools. For [server tools](https://docs.claude.com/en/docs/agents-and-tools/tool-use/overview#server-tools), see their individual documentation as each has its own behavior (e.g., the [web search tool](https://docs.claude.com/en/docs/agents-and-tools/tool-use/web-search-tool)).

  Each tool definition includes:

  * `name`: Name of the tool.
  * `description`: Optional, but strongly-recommended description of the tool.
  * `input_schema`: [JSON schema](https://json-schema.org/draft/2020-12) for the tool `input` shape that the model will produce in `tool_use` output content blocks.

  For example, if you defined `tools` as:

  ```json
  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]
  ```

  And then asked the model "What's the S&P 500 at today?", the model might produce `tool_use` content blocks in the response like this:

  ```json
  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]
  ```

  You might then run your `get_stock_price` tool with `{"ticker": "^GSPC"}` as an input, and return the following back to the model in a subsequent `user` message:

  ```json
  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]
  ```

  Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

  See our [guide](https://docs.claude.com/en/docs/tool-use) for more details.

  - `class BetaTool`

    - `input_schema: InputSchema{ type, properties, required}`

      [JSON schema](https://json-schema.org/draft/2020-12) for this tool's input.

      This defines the shape of the `input` that your tool accepts and that the model will produce.

      - `type: :object`

        - `:object`

      - `properties: Hash[Symbol, untyped]`

      - `required: Array[String]`

    - `name: String`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `description: String`

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    - `eager_input_streaming: bool`

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `type: :custom`

      - `:custom`

  - `class BetaToolBash20241022`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20241022`

      - `:bash_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolBash20250124`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20250124`

      - `:bash_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250522`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250522`

      - `:code_execution_20250522`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250825`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250825`

      - `:code_execution_20250825`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20260120`

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20260120`

      - `:code_execution_20260120`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20241022`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20241022`

      - `:computer_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMemoryTool20250818`

    - `name: :memory`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:memory`

    - `type: :memory_20250818`

      - `:memory_20250818`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20250124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20250124`

      - `:computer_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20241022`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20241022`

      - `:text_editor_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20251124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20251124`

      - `:computer_20251124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `enable_zoom: bool`

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250124`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20250124`

      - `:text_editor_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250429`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250429`

      - `:text_editor_20250429`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250728`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250728`

      - `:text_editor_20250728`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `max_characters: Integer`

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20250305`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20250305`

      - `:web_search_20250305`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

      - `type: :approximate`

        - `:approximate`

      - `city: String`

        The city of the user.

      - `country: String`

        The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

      - `region: String`

        The region of the user.

      - `timezone: String`

        The [IANA timezone](https://nodatime.org/TimeZones) of the user.

  - `class BetaWebFetchTool20250910`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20250910`

      - `:web_fetch_20250910`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20260209`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20260209`

      - `:web_search_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

  - `class BetaWebFetchTool20260209`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260209`

      - `:web_fetch_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebFetchTool20260309`

    Web fetch tool with use_cache parameter for bypassing cached content.

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260309`

      - `:web_fetch_20260309`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `use_cache: bool`

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  - `class BetaAdvisorTool20260301`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `name: :advisor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:advisor`

    - `type: :advisor_20260301`

      - `:advisor_20260301`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caching: BetaCacheControlEphemeral`

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_tokens: Integer`

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolBm25_20251119`

    - `name: :tool_search_tool_bm25`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_bm25`

    - `type: :tool_search_tool_bm25_20251119 | :tool_search_tool_bm25`

      - `:tool_search_tool_bm25_20251119`

      - `:tool_search_tool_bm25`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolRegex20251119`

    - `name: :tool_search_tool_regex`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_regex`

    - `type: :tool_search_tool_regex_20251119 | :tool_search_tool_regex`

      - `:tool_search_tool_regex_20251119`

      - `:tool_search_tool_regex`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMCPToolset`

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools
    from an MCP server, with optional per-tool overrides.

    - `mcp_server_name: String`

      Name of the MCP server to configure tools for

    - `type: :mcp_toolset`

      - `:mcp_toolset`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `configs: Hash[Symbol, BetaMCPToolConfig]`

      Configuration overrides for specific tools, keyed by tool name

      - `defer_loading: bool`

      - `enabled: bool`

    - `default_config: BetaMCPToolDefaultConfig`

      Default configuration applied to all tools from this server

      - `defer_loading: bool`

      - `enabled: bool`

- `top_k: Integer`

  Only sample from the top K options for each subsequent token.

  Used to remove "long tail" low probability responses. [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277).

  Recommended for advanced use cases only.

- `top_p: Float`

  Use nucleus sampling.

  In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by `top_p`.

  Recommended for advanced use cases only.

- `user_profile_id: String`

  The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessage`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `container: BetaContainer`

    Information about the container used in the request (for the code execution tool)

    - `id: String`

      Identifier for the container used in this request

    - `expires_at: Time`

      The time at which the container will expire.

    - `skills: Array[BetaSkill]`

      Skills loaded in the container

      - `skill_id: String`

        Skill ID

      - `type: :anthropic | :custom`

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        - `:anthropic`

        - `:custom`

      - `version: String`

        Skill version or 'latest' for most recent version

  - `content: Array[BetaContentBlock]`

    Content generated by the model.

    This is an array of content blocks, each of which has a `type` that determines its shape.

    Example:

    ```json
    [{"type": "text", "text": "Hi, I'm Claude."}]
    ```

    If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

    For example, if the input `messages` were:

    ```json
    [
      {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
      {"role": "assistant", "content": "The best answer is ("}
    ]
    ```

    Then the response `content` might be:

    ```json
    [{"type": "text", "text": "B)"}]
    ```

    - `class BetaTextBlock`

      - `citations: Array[BetaTextCitation]`

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

        - `class BetaCitationCharLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `file_id: String`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `file_id: String`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `file_id: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationsWebSearchResultLocation`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

      - `text: String`

      - `type: :text`

        - `:text`

    - `class BetaThinkingBlock`

      - `signature: String`

      - `thinking: String`

      - `type: :thinking`

        - `:thinking`

    - `class BetaRedactedThinkingBlock`

      - `data: String`

      - `type: :redacted_thinking`

        - `:redacted_thinking`

    - `class BetaToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

      - `type: :tool_use`

        - `:tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

          - `type: :direct`

            - `:direct`

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

          - `tool_id: String`

          - `type: :code_execution_20250825`

            - `:code_execution_20250825`

        - `class BetaServerToolCaller20260120`

          - `tool_id: String`

          - `type: :code_execution_20260120`

            - `:code_execution_20260120`

    - `class BetaServerToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: :advisor | :web_search | :web_fetch | 5 more`

        - `:advisor`

        - `:web_search`

        - `:web_fetch`

        - `:code_execution`

        - `:bash_code_execution`

        - `:text_editor_code_execution`

        - `:tool_search_tool_regex`

        - `:tool_search_tool_bm25`

      - `type: :server_tool_use`

        - `:server_tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebSearchToolResultBlock`

      - `content: BetaWebSearchToolResultBlockContent`

        - `class BetaWebSearchToolResultError`

          - `error_code: BetaWebSearchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:max_uses_exceeded`

            - `:too_many_requests`

            - `:query_too_long`

            - `:request_too_large`

          - `type: :web_search_tool_result_error`

            - `:web_search_tool_result_error`

        - `UnionMember1 = Array[BetaWebSearchResultBlock]`

          - `encrypted_content: String`

          - `page_age: String`

          - `title: String`

          - `type: :web_search_result`

            - `:web_search_result`

          - `url: String`

      - `tool_use_id: String`

      - `type: :web_search_tool_result`

        - `:web_search_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebFetchToolResultBlock`

      - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

        - `class BetaWebFetchToolResultErrorBlock`

          - `error_code: BetaWebFetchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:url_too_long`

            - `:url_not_allowed`

            - `:url_not_in_prior_context`

            - `:url_not_accessible`

            - `:unsupported_content_type`

            - `:too_many_requests`

            - `:max_uses_exceeded`

            - `:unavailable`

          - `type: :web_fetch_tool_result_error`

            - `:web_fetch_tool_result_error`

        - `class BetaWebFetchBlock`

          - `content: BetaDocumentBlock`

            - `citations: BetaCitationConfig`

              Citation configuration for the document

              - `enabled: bool`

            - `source: BetaBase64PDFSource | BetaPlainTextSource`

              - `class BetaBase64PDFSource`

                - `data: String`

                - `media_type: :"application/pdf"`

                  - `:"application/pdf"`

                - `type: :base64`

                  - `:base64`

              - `class BetaPlainTextSource`

                - `data: String`

                - `media_type: :"text/plain"`

                  - `:"text/plain"`

                - `type: :text`

                  - `:text`

            - `title: String`

              The title of the document

            - `type: :document`

              - `:document`

          - `retrieved_at: String`

            ISO 8601 timestamp when the content was retrieved

          - `type: :web_fetch_result`

            - `:web_fetch_result`

          - `url: String`

            Fetched content URL

      - `tool_use_id: String`

      - `type: :web_fetch_tool_result`

        - `:web_fetch_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaAdvisorToolResultBlock`

      - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

        - `class BetaAdvisorToolResultError`

          - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

            - `:max_uses_exceeded`

            - `:prompt_too_long`

            - `:too_many_requests`

            - `:overloaded`

            - `:unavailable`

            - `:execution_time_exceeded`

            - `:model_not_found`

          - `type: :advisor_tool_result_error`

            - `:advisor_tool_result_error`

        - `class BetaAdvisorResultBlock`

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

          - `text: String`

          - `type: :advisor_result`

            - `:advisor_result`

        - `class BetaAdvisorRedactedResultBlock`

          - `encrypted_content: String`

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

          - `type: :advisor_redacted_result`

            - `:advisor_redacted_result`

      - `tool_use_id: String`

      - `type: :advisor_tool_result`

        - `:advisor_tool_result`

    - `class BetaCodeExecutionToolResultBlock`

      - `content: BetaCodeExecutionToolResultBlockContent`

        Code execution result with encrypted stdout for PFC + web_search results.

        - `class BetaCodeExecutionToolResultError`

          - `error_code: BetaCodeExecutionToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `type: :code_execution_tool_result_error`

            - `:code_execution_tool_result_error`

        - `class BetaCodeExecutionResultBlock`

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

              - `:code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :code_execution_result`

            - `:code_execution_result`

        - `class BetaEncryptedCodeExecutionResultBlock`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

          - `encrypted_stdout: String`

          - `return_code: Integer`

          - `stderr: String`

          - `type: :encrypted_code_execution_result`

            - `:encrypted_code_execution_result`

      - `tool_use_id: String`

      - `type: :code_execution_tool_result`

        - `:code_execution_tool_result`

    - `class BetaBashCodeExecutionToolResultBlock`

      - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

        - `class BetaBashCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:output_file_too_large`

          - `type: :bash_code_execution_tool_result_error`

            - `:bash_code_execution_tool_result_error`

        - `class BetaBashCodeExecutionResultBlock`

          - `content: Array[BetaBashCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :bash_code_execution_output`

              - `:bash_code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :bash_code_execution_result`

            - `:bash_code_execution_result`

      - `tool_use_id: String`

      - `type: :bash_code_execution_tool_result`

        - `:bash_code_execution_tool_result`

    - `class BetaTextEditorCodeExecutionToolResultBlock`

      - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

        - `class BetaTextEditorCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:file_not_found`

          - `error_message: String`

          - `type: :text_editor_code_execution_tool_result_error`

            - `:text_editor_code_execution_tool_result_error`

        - `class BetaTextEditorCodeExecutionViewResultBlock`

          - `content: String`

          - `file_type: :text | :image | :pdf`

            - `:text`

            - `:image`

            - `:pdf`

          - `num_lines: Integer`

          - `start_line: Integer`

          - `total_lines: Integer`

          - `type: :text_editor_code_execution_view_result`

            - `:text_editor_code_execution_view_result`

        - `class BetaTextEditorCodeExecutionCreateResultBlock`

          - `is_file_update: bool`

          - `type: :text_editor_code_execution_create_result`

            - `:text_editor_code_execution_create_result`

        - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

          - `lines: Array[String]`

          - `new_lines: Integer`

          - `new_start: Integer`

          - `old_lines: Integer`

          - `old_start: Integer`

          - `type: :text_editor_code_execution_str_replace_result`

            - `:text_editor_code_execution_str_replace_result`

      - `tool_use_id: String`

      - `type: :text_editor_code_execution_tool_result`

        - `:text_editor_code_execution_tool_result`

    - `class BetaToolSearchToolResultBlock`

      - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

        - `class BetaToolSearchToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `error_message: String`

          - `type: :tool_search_tool_result_error`

            - `:tool_search_tool_result_error`

        - `class BetaToolSearchToolSearchResultBlock`

          - `tool_references: Array[BetaToolReferenceBlock]`

            - `tool_name: String`

            - `type: :tool_reference`

              - `:tool_reference`

          - `type: :tool_search_tool_search_result`

            - `:tool_search_tool_search_result`

      - `tool_use_id: String`

      - `type: :tool_search_tool_result`

        - `:tool_search_tool_result`

    - `class BetaMCPToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

        The name of the MCP tool

      - `server_name: String`

        The name of the MCP server

      - `type: :mcp_tool_use`

        - `:mcp_tool_use`

    - `class BetaMCPToolResultBlock`

      - `content: String | Array[BetaTextBlock]`

        - `String = String`

        - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

          - `citations: Array[BetaTextCitation]`

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

          - `text: String`

          - `type: :text`

      - `is_error: bool`

      - `tool_use_id: String`

      - `type: :mcp_tool_result`

        - `:mcp_tool_result`

    - `class BetaContainerUploadBlock`

      Response model for a file uploaded to the container.

      - `file_id: String`

      - `type: :container_upload`

        - `:container_upload`

    - `class BetaCompactionBlock`

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid
      summary (e.g., malformed output from the model). Clients may round-trip
      compaction blocks with null content; the server treats them as no-ops.

      - `content: String`

        Summary of compacted content, or null if compaction failed

      - `encrypted_content: String`

        Opaque metadata from prior compaction, to be round-tripped verbatim

      - `type: :compaction`

        - `:compaction`

    - `class BetaFallbackBlock`

      Marks the point in `content` where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and
      declined. A turn routed directly by the sticky decision has no such boundary
      and carries no block — the signal for whether a fallback model served the
      response is the presence of a `fallback_message` entry in
      `usage.iterations`, not this block.

      The block is treated like a server-tool content block for streaming: it
      arrives via the standard `content_block_start` / `content_block_stop`
      pair and carries no deltas.

      - `from: BetaFallbackInfo`

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `:"claude-fable-5"`

              Next generation of intelligence for the hardest knowledge work and coding problems

            - `:"claude-mythos-5"`

              Most capable model for cybersecurity and biology research

            - `:"claude-opus-4-8"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-opus-4-7"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-mythos-preview"`

              New class of intelligence, strongest in coding and cybersecurity

            - `:"claude-opus-4-6"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-sonnet-4-6"`

              Best combination of speed and intelligence

            - `:"claude-haiku-4-5"`

              Fastest model with near-frontier intelligence

            - `:"claude-haiku-4-5-20251001"`

              Fastest model with near-frontier intelligence

            - `:"claude-opus-4-5"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-opus-4-5-20251101"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-sonnet-4-5"`

              High-performance model for agents and coding

            - `:"claude-sonnet-4-5-20250929"`

              High-performance model for agents and coding

            - `:"claude-opus-4-1"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-1-20250805"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-0"`

              Powerful model for complex tasks

            - `:"claude-opus-4-20250514"`

              Powerful model for complex tasks

            - `:"claude-sonnet-4-0"`

              High-performance model with extended thinking

            - `:"claude-sonnet-4-20250514"`

              High-performance model with extended thinking

            - `:"claude-3-haiku-20240307"`

              Fast and cost-effective model

          - `String = String`

      - `to: BetaFallbackInfo`

        The fallback model producing the content that follows this block. Its `model` is always the canonical id.

      - `type: :fallback`

        - `:fallback`

  - `context_management: BetaContextManagementResponse`

    Context management response.

    Information about context management strategies applied during the request.

    - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

      List of context management edits that were applied.

      - `class BetaClearToolUses20250919EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_tool_uses: Integer`

          Number of tool uses that were cleared.

        - `type: :clear_tool_uses_20250919`

          The type of context management edit applied.

          - `:clear_tool_uses_20250919`

      - `class BetaClearThinking20251015EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_thinking_turns: Integer`

          Number of thinking turns that were cleared.

        - `type: :clear_thinking_20251015`

          The type of context management edit applied.

          - `:clear_thinking_20251015`

  - `diagnostics: BetaDiagnostics`

    Response envelope for request-level diagnostics. Present (possibly
    null) whenever the caller supplied `diagnostics` on the request.

    - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

      Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

      - `class BetaCacheMissModelChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :model_changed`

          - `:model_changed`

      - `class BetaCacheMissSystemChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :system_changed`

          - `:system_changed`

      - `class BetaCacheMissToolsChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :tools_changed`

          - `:tools_changed`

      - `class BetaCacheMissMessagesChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :messages_changed`

          - `:messages_changed`

      - `class BetaCacheMissPreviousMessageNotFound`

        - `type: :previous_message_not_found`

          - `:previous_message_not_found`

      - `class BetaCacheMissUnavailable`

        - `type: :unavailable`

          - `:unavailable`

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

  - `role: :assistant`

    Conversational role of the generated message.

    This will always be `"assistant"`.

    - `:assistant`

  - `stop_details: BetaRefusalStopDetails`

    Structured information about a refusal.

    - `category: :cyber | :bio | :reasoning_extraction`

      The policy category that triggered the refusal.

      `null` when the refusal doesn't map to a named category.

      - `:cyber`

      - `:bio`

      - `:reasoning_extraction`

    - `explanation: String`

      Human-readable explanation of the refusal.

      This text is not guaranteed to be stable. `null` when no explanation is available for the category.

    - `fallback_credit_token: String`

      Opaque code that refunds the cache-miss cost when retrying this refused
      request on the fallback model. Pass it as `fallback_credit_token` on the
      retry request. Expires 5 minutes after the refusal.

      The retry is sent either with the same request body (`system`, `messages`,
      `tools`, and other render-shaping fields), or with the same body plus one
      appended `assistant` message whose content is the partial text (with any
      trailing whitespace stripped from the final text block) and paired
      server-tool blocks from this refusal — which also authorizes that
      appended turn as an assistant-prefill continuation on models that otherwise
      disallow prefill. A token minted mid-server-tool-loop whose partial content
      was continuable may only be redeemed the second way — if a same-body retry
      is rejected with a 400 saying the token must be redeemed by continuing the
      partial response, retry the second way instead. Either way: same workspace,
      same platform; a mismatch is a 400. Resending a token for an already-warm
      prefix is permitted but yields no additional credit.

      `null` when the refused model isn't eligible for a fallback credit.

    - `fallback_has_prefill_claim: bool`

      Whether the accompanying `fallback_credit_token` may be redeemed with the
      appended-assistant retry form. Only set when `fallback_credit_token` is
      present.

      `true`: retry by resending the same request body plus one appended
      `assistant` message whose content is this response's `content` with any
      trailing whitespace stripped from the final text block and unpaired
      `tool_use` blocks omitted (the same appended-turn shape described on
      `fallback_credit_token`), with the token attached. `false`: retry by
      resending the original request body unchanged, with the token attached —
      the appended-assistant form is not available for this refusal (no
      continuable partial content, or the request uses `output_format` or a
      `tool_choice` that forces tool use). One exception: when the request used
      `output_format` or a forced `tool_choice` and the refusal arrived after
      server tools (including MCP connector tools) had already executed, the
      token may not be redeemable by either retry form; if the exact-body retry
      is then rejected with a 400 saying the token must be redeemed by
      continuing the partial response, discard the token and retry without it.

      Advisory: if an appended-assistant retry is rejected with a 400 despite
      `true`, fall back to resending the original request body with the token.

    - `recommended_model: String`

      The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

    - `type: :refusal`

      - `:refusal`

  - `stop_reason: BetaStopReason`

    The reason that we stopped.

    This may be one the following values:

    * `"end_turn"`: the model reached a natural stopping point
    * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
    * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
    * `"tool_use"`: the model invoked one or more tools
    * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
    * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

    In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

    - `:end_turn`

    - `:max_tokens`

    - `:stop_sequence`

    - `:tool_use`

    - `:pause_turn`

    - `:compaction`

    - `:refusal`

    - `:model_context_window_exceeded`

  - `stop_sequence: String`

    Which custom stop sequence was generated, if any.

    This value will be a non-null string if one of your custom stop sequences was generated.

  - `type: :message`

    Object type.

    For Messages, this is always `"message"`.

    - `:message`

  - `usage: BetaUsage`

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

    For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

      - `ephemeral_1h_input_tokens: Integer`

        The number of input tokens used to create the 1 hour cache entry.

      - `ephemeral_5m_input_tokens: Integer`

        The number of input tokens used to create the 5 minute cache entry.

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `inference_geo: String`

      The geographic region where inference was performed for this request.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `iterations: BetaIterationsUsage`

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

      - Determine which iterations exceeded long context thresholds (>=200k tokens)
      - Calculate the true context window size from the last iteration
      - Understand token accumulation across server-side tool use loops

      - `class BetaMessageIterationUsage`

        Token usage for a sampling iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :message`

          Usage for a sampling iteration

          - `:message`

      - `class BetaCompactionIterationUsage`

        Token usage for a compaction iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :compaction`

          Usage for a compaction iteration

          - `:compaction`

      - `class BetaAdvisorMessageIterationUsage`

        Token usage for an advisor sub-inference iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :advisor_message`

          Usage for an advisor sub-inference iteration

          - `:advisor_message`

      - `class BetaFallbackMessageIterationUsage`

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a `message` entry for whichever hop served the
        response. A declined hop produces the existing `message` entry. Whether
        a fallback model served the response is signalled by the presence of this
        entry in `usage.iterations`.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :fallback_message`

          Usage for the fallback-model attempt that served the response

          - `:fallback_message`

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `output_tokens_details: BetaOutputTokensDetails`

      Breakdown of output tokens by category.

      `output_tokens` remains the inclusive, authoritative total used for billing.
      This object provides a read-only decomposition for observability — for example,
      how many of the billed output tokens were spent on internal reasoning that may
      have been summarized before being returned to you.

      - `thinking_tokens: Integer`

        Number of output tokens the model generated as internal reasoning, including
        the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter)
        summarized thinking text returned in the response body. Computed by
        re-tokenizing the raw reasoning text, so it may differ from the model's exact
        generation count by a small number of tokens. Always ≤ `output_tokens`;
        `output_tokens - thinking_tokens` approximates the non-reasoning output.

    - `server_tool_use: BetaServerToolUsage`

      The number of server tool requests.

      - `web_fetch_requests: Integer`

        The number of web fetch tool requests.

      - `web_search_requests: Integer`

        The number of web search tool requests.

    - `service_tier: :standard | :priority | :batch`

      If the request used the priority, standard, or batch tier.

      - `:standard`

      - `:priority`

      - `:batch`

    - `speed: :standard | :fast`

      The inference speed mode used for this request.

      - `:standard`

      - `:fast`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message = anthropic.beta.messages.create(
  max_tokens: 1024,
  messages: [{content: "Hello, world", role: :user}],
  model: :"claude-opus-4-6"
)

puts(beta_message)
```

#### Response

```json
{
  "id": "msg_013Zva2CMHLNnXjNJJKqJ2EF",
  "container": {
    "id": "id",
    "expires_at": "2019-12-27T18:11:19.117Z",
    "skills": [
      {
        "skill_id": "pdf",
        "type": "anthropic",
        "version": "latest"
      }
    ]
  },
  "content": [
    {
      "citations": [
        {
          "cited_text": "cited_text",
          "document_index": 0,
          "document_title": "document_title",
          "end_char_index": 0,
          "file_id": "file_id",
          "start_char_index": 0,
          "type": "char_location"
        }
      ],
      "text": "Hi! My name is Claude.",
      "type": "text"
    }
  ],
  "context_management": {
    "applied_edits": [
      {
        "cleared_input_tokens": 0,
        "cleared_tool_uses": 0,
        "type": "clear_tool_uses_20250919"
      }
    ]
  },
  "diagnostics": {
    "cache_miss_reason": {
      "cache_missed_input_tokens": 0,
      "type": "model_changed"
    }
  },
  "model": "claude-opus-4-6",
  "role": "assistant",
  "stop_details": {
    "category": "cyber",
    "explanation": "explanation",
    "fallback_credit_token": "fallback_credit_token",
    "fallback_has_prefill_claim": true,
    "recommended_model": "recommended_model",
    "type": "refusal"
  },
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "type": "message",
  "usage": {
    "cache_creation": {
      "ephemeral_1h_input_tokens": 0,
      "ephemeral_5m_input_tokens": 0
    },
    "cache_creation_input_tokens": 2051,
    "cache_read_input_tokens": 2051,
    "inference_geo": "inference_geo",
    "input_tokens": 2095,
    "iterations": [
      {
        "cache_creation": {
          "ephemeral_1h_input_tokens": 0,
          "ephemeral_5m_input_tokens": 0
        },
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0,
        "input_tokens": 0,
        "model": "claude-fable-5",
        "output_tokens": 0,
        "type": "message"
      }
    ],
    "output_tokens": 503,
    "output_tokens_details": {
      "thinking_tokens": 0
    },
    "server_tool_use": {
      "web_fetch_requests": 2,
      "web_search_requests": 0
    },
    "service_tier": "standard",
    "speed": "standard"
  }
}
```

## Count tokens in a Message

`beta.messages.count_tokens(**kwargs) -> BetaMessageTokensCount`

**post** `/v1/messages/count_tokens`

Count the number of tokens in a Message.

The Token Count API can be used to count the number of tokens in a Message, including tools, images, and documents, without creating it.

Learn more about token counting in our [user guide](https://docs.claude.com/en/docs/build-with-claude/token-counting)

### Parameters

- `messages: Array[BetaMessageParam]`

  Input messages.

  Our models are trained to operate on alternating `user` and `assistant` conversational turns. When creating a new `Message`, you specify the prior conversational turns with the `messages` parameter, and the model then generates the next `Message` in the conversation. Consecutive `user` or `assistant` turns in your request will be combined into a single turn.

  Each input message must be an object with a `role` and `content`. You can specify a single `user`-role message, or you can include multiple `user` and `assistant` messages.

  If the final message uses the `assistant` role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

  Example with a single `user` message:

  ```json
  [{"role": "user", "content": "Hello, Claude"}]
  ```

  Example with multiple conversational turns:

  ```json
  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]
  ```

  Example with a partially-filled response from Claude:

  ```json
  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]
  ```

  Each input message `content` may be either a single `string` or an array of content blocks, where each block has a specific `type`. Using a `string` for `content` is shorthand for an array of one content block of type `"text"`. The following input messages are equivalent:

  ```json
  {"role": "user", "content": "Hello, Claude"}
  ```

  ```json
  {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}
  ```

  See [input examples](https://docs.claude.com/en/api/messages-examples).

  Note that if you want to include a [system prompt](https://docs.claude.com/en/docs/system-prompts), you can use the top-level `system` parameter — there is no `"system"` role for input messages in the Messages API.

  There is a limit of 100,000 messages in a single request.

  - `content: String | Array[BetaContentBlockParam]`

    - `String = String`

    - `UnionMember1 = Array[BetaContentBlockParam]`

      - `class BetaTextBlockParam`

        - `text: String`

        - `type: :text`

          - `:text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

          - `type: :ephemeral`

            - `:ephemeral`

          - `ttl: :"5m" | :"1h"`

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            - `5m`: 5 minutes
            - `1h`: 1 hour

            Defaults to `5m`.

            - `:"5m"`

            - `:"1h"`

        - `citations: Array[BetaTextCitationParam]`

          - `class BetaCitationCharLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationWebSearchResultLocationParam`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

      - `class BetaImageBlockParam`

        - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

          - `class BetaBase64ImageSource`

            - `data: String`

            - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

              - `:"image/jpeg"`

              - `:"image/png"`

              - `:"image/gif"`

              - `:"image/webp"`

            - `type: :base64`

              - `:base64`

          - `class BetaURLImageSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileImageSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :image`

          - `:image`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestDocumentBlock`

        - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

          - `class BetaContentBlockSource`

            - `content: String | Array[BetaContentBlockSourceContent]`

              - `String = String`

              - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                - `class BetaTextBlockParam`

                - `class BetaImageBlockParam`

            - `type: :content`

              - `:content`

          - `class BetaURLPDFSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileDocumentSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :document`

          - `:document`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          - `enabled: bool`

        - `context: String`

        - `title: String`

      - `class BetaSearchResultBlockParam`

        - `content: Array[BetaTextBlockParam]`

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `source: String`

        - `title: String`

        - `type: :search_result`

          - `:search_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

      - `class BetaThinkingBlockParam`

        - `signature: String`

        - `thinking: String`

        - `type: :thinking`

          - `:thinking`

      - `class BetaRedactedThinkingBlockParam`

        - `data: String`

        - `type: :redacted_thinking`

          - `:redacted_thinking`

      - `class BetaToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `type: :tool_use`

          - `:tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

            - `type: :direct`

              - `:direct`

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

            - `tool_id: String`

            - `type: :code_execution_20250825`

              - `:code_execution_20250825`

          - `class BetaServerToolCaller20260120`

            - `tool_id: String`

            - `type: :code_execution_20260120`

              - `:code_execution_20260120`

      - `class BetaToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :tool_result`

          - `:tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

          - `String = String`

          - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

            - `class BetaTextBlockParam`

            - `class BetaImageBlockParam`

            - `class BetaSearchResultBlockParam`

            - `class BetaRequestDocumentBlock`

            - `class BetaToolReferenceBlockParam`

              Tool reference block that can be included in tool_result content.

              - `tool_name: String`

              - `type: :tool_reference`

                - `:tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

        - `is_error: bool`

      - `class BetaServerToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: :advisor | :web_search | :web_fetch | 5 more`

          - `:advisor`

          - `:web_search`

          - `:web_fetch`

          - `:code_execution`

          - `:bash_code_execution`

          - `:text_editor_code_execution`

          - `:tool_search_tool_regex`

          - `:tool_search_tool_bm25`

        - `type: :server_tool_use`

          - `:server_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebSearchToolResultBlockParam`

        - `content: BetaWebSearchToolResultBlockParamContent`

          - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

            - `encrypted_content: String`

            - `title: String`

            - `type: :web_search_result`

              - `:web_search_result`

            - `url: String`

            - `page_age: String`

          - `class BetaWebSearchToolRequestError`

            - `error_code: BetaWebSearchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:max_uses_exceeded`

              - `:too_many_requests`

              - `:query_too_long`

              - `:request_too_large`

            - `type: :web_search_tool_result_error`

              - `:web_search_tool_result_error`

        - `tool_use_id: String`

        - `type: :web_search_tool_result`

          - `:web_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebFetchToolResultBlockParam`

        - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

          - `class BetaWebFetchToolResultErrorBlockParam`

            - `error_code: BetaWebFetchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:url_too_long`

              - `:url_not_allowed`

              - `:url_not_in_prior_context`

              - `:url_not_accessible`

              - `:unsupported_content_type`

              - `:too_many_requests`

              - `:max_uses_exceeded`

              - `:unavailable`

            - `type: :web_fetch_tool_result_error`

              - `:web_fetch_tool_result_error`

          - `class BetaWebFetchBlockParam`

            - `content: BetaRequestDocumentBlock`

            - `type: :web_fetch_result`

              - `:web_fetch_result`

            - `url: String`

              Fetched content URL

            - `retrieved_at: String`

              ISO 8601 timestamp when the content was retrieved

        - `tool_use_id: String`

        - `type: :web_fetch_tool_result`

          - `:web_fetch_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaAdvisorToolResultBlockParam`

        - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

          - `class BetaAdvisorToolResultErrorParam`

            - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

              - `:max_uses_exceeded`

              - `:prompt_too_long`

              - `:too_many_requests`

              - `:overloaded`

              - `:unavailable`

              - `:execution_time_exceeded`

              - `:model_not_found`

            - `type: :advisor_tool_result_error`

              - `:advisor_tool_result_error`

          - `class BetaAdvisorResultBlockParam`

            - `text: String`

            - `type: :advisor_result`

              - `:advisor_result`

            - `stop_reason: String`

          - `class BetaAdvisorRedactedResultBlockParam`

            - `encrypted_content: String`

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            - `type: :advisor_redacted_result`

              - `:advisor_redacted_result`

            - `stop_reason: String`

        - `tool_use_id: String`

        - `type: :advisor_tool_result`

          - `:advisor_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCodeExecutionToolResultBlockParam`

        - `content: BetaCodeExecutionToolResultBlockParamContent`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `class BetaCodeExecutionToolResultErrorParam`

            - `error_code: BetaCodeExecutionToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :code_execution_tool_result_error`

              - `:code_execution_tool_result_error`

          - `class BetaCodeExecutionResultBlockParam`

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

                - `:code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :code_execution_result`

              - `:code_execution_result`

          - `class BetaEncryptedCodeExecutionResultBlockParam`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

            - `encrypted_stdout: String`

            - `return_code: Integer`

            - `stderr: String`

            - `type: :encrypted_code_execution_result`

              - `:encrypted_code_execution_result`

        - `tool_use_id: String`

        - `type: :code_execution_tool_result`

          - `:code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaBashCodeExecutionToolResultBlockParam`

        - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

          - `class BetaBashCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:output_file_too_large`

            - `type: :bash_code_execution_tool_result_error`

              - `:bash_code_execution_tool_result_error`

          - `class BetaBashCodeExecutionResultBlockParam`

            - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :bash_code_execution_output`

                - `:bash_code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :bash_code_execution_result`

              - `:bash_code_execution_result`

        - `tool_use_id: String`

        - `type: :bash_code_execution_tool_result`

          - `:bash_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaTextEditorCodeExecutionToolResultBlockParam`

        - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

          - `class BetaTextEditorCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:file_not_found`

            - `type: :text_editor_code_execution_tool_result_error`

              - `:text_editor_code_execution_tool_result_error`

            - `error_message: String`

          - `class BetaTextEditorCodeExecutionViewResultBlockParam`

            - `content: String`

            - `file_type: :text | :image | :pdf`

              - `:text`

              - `:image`

              - `:pdf`

            - `type: :text_editor_code_execution_view_result`

              - `:text_editor_code_execution_view_result`

            - `num_lines: Integer`

            - `start_line: Integer`

            - `total_lines: Integer`

          - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

            - `is_file_update: bool`

            - `type: :text_editor_code_execution_create_result`

              - `:text_editor_code_execution_create_result`

          - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

            - `type: :text_editor_code_execution_str_replace_result`

              - `:text_editor_code_execution_str_replace_result`

            - `lines: Array[String]`

            - `new_lines: Integer`

            - `new_start: Integer`

            - `old_lines: Integer`

            - `old_start: Integer`

        - `tool_use_id: String`

        - `type: :text_editor_code_execution_tool_result`

          - `:text_editor_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaToolSearchToolResultBlockParam`

        - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

          - `class BetaToolSearchToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :tool_search_tool_result_error`

              - `:tool_search_tool_result_error`

            - `error_message: String`

          - `class BetaToolSearchToolSearchResultBlockParam`

            - `tool_references: Array[BetaToolReferenceBlockParam]`

              - `tool_name: String`

              - `type: :tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

            - `type: :tool_search_tool_search_result`

              - `:tool_search_tool_search_result`

        - `tool_use_id: String`

        - `type: :tool_search_tool_result`

          - `:tool_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaMCPToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `server_name: String`

          The name of the MCP server

        - `type: :mcp_tool_use`

          - `:mcp_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestMCPToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :mcp_tool_result`

          - `:mcp_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam]`

          - `String = String`

          - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

            - `text: String`

            - `type: :text`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `citations: Array[BetaTextCitationParam]`

        - `is_error: bool`

      - `class BetaContainerUploadBlockParam`

        A content block that represents a file to be uploaded to the container
        Files uploaded via this block will be available in the container's input directory.

        - `file_id: String`

        - `type: :container_upload`

          - `:container_upload`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCompactionBlockParam`

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests
        to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server
        treats these as no-ops. Empty string content is not allowed.

        - `type: :compaction`

          - `:compaction`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String`

          Summary of previously compacted content, or null if compaction failed

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

      - `class BetaMidConversationSystemBlockParam`

        System instructions that appear mid-conversation.

        Use this block to provide or update system-level instructions at a specific
        point in the conversation, rather than only via the top-level `system` parameter.

        - `content: Array[BetaTextBlockParam]`

          System instruction text blocks.

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `type: :mid_conv_system`

          - `:mid_conv_system`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaFallbackBlockParam`

        A `fallback` block echoed back from a prior response.

        Accepted in `messages[].content` and never rendered into the prompt,
        not validated against the request's `fallbacks` chain or top-level
        `model`, and stripped before the sticky-routing cache key is computed.

        Callers should echo the assistant turn verbatim — block included. The
        block's position is load-bearing for thinking verification: the thinking
        runs on either side of a fallback hop carry independently-rooted
        verification hash chains, and this block is the only record of where one
        chain ends and the next begins. When thinking runs flank the boundary,
        omitting the block merges the runs into one contiguous span whose hashes
        cannot verify (the request is rejected), and moving it into the middle of
        a single run splits that run's chain and is likewise rejected; between
        non-thinking blocks the block's placement has no verification effect.

        - `from: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `:"claude-fable-5"`

                Next generation of intelligence for the hardest knowledge work and coding problems

              - `:"claude-mythos-5"`

                Most capable model for cybersecurity and biology research

              - `:"claude-opus-4-8"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-opus-4-7"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-mythos-preview"`

                New class of intelligence, strongest in coding and cybersecurity

              - `:"claude-opus-4-6"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-sonnet-4-6"`

                Best combination of speed and intelligence

              - `:"claude-haiku-4-5"`

                Fastest model with near-frontier intelligence

              - `:"claude-haiku-4-5-20251001"`

                Fastest model with near-frontier intelligence

              - `:"claude-opus-4-5"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-opus-4-5-20251101"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-sonnet-4-5"`

                High-performance model for agents and coding

              - `:"claude-sonnet-4-5-20250929"`

                High-performance model for agents and coding

              - `:"claude-opus-4-1"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-1-20250805"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-0"`

                Powerful model for complex tasks

              - `:"claude-opus-4-20250514"`

                Powerful model for complex tasks

              - `:"claude-sonnet-4-0"`

                High-performance model with extended thinking

              - `:"claude-sonnet-4-20250514"`

                High-performance model with extended thinking

              - `:"claude-3-haiku-20240307"`

                Fast and cost-effective model

            - `String = String`

        - `to: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

        - `type: :fallback`

          - `:fallback`

  - `role: :user | :assistant | :system`

    - `:user`

    - `:assistant`

    - `:system`

- `model: Model`

  The model that will complete your prompt.

  See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

- `cache_control: BetaCacheControlEphemeral`

  Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

- `context_management: BetaContextManagementConfig`

  Context management configuration.

  This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

  - `edits: Array[BetaClearToolUses20250919Edit | BetaClearThinking20251015Edit | BetaCompact20260112Edit]`

    List of context management edits to apply

    - `class BetaClearToolUses20250919Edit`

      - `type: :clear_tool_uses_20250919`

        - `:clear_tool_uses_20250919`

      - `clear_at_least: BetaInputTokensClearAtLeast`

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        - `type: :input_tokens`

          - `:input_tokens`

        - `value: Integer`

      - `clear_tool_inputs: bool | Array[String]`

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        - `UnionMember0 = bool`

        - `UnionMember1 = Array[String]`

      - `exclude_tools: Array[String]`

        Tool names whose uses are preserved from clearing

      - `keep: BetaToolUsesKeep`

        Number of tool uses to retain in the conversation

        - `type: :tool_uses`

          - `:tool_uses`

        - `value: Integer`

      - `trigger: BetaInputTokensTrigger | BetaToolUsesTrigger`

        Condition that triggers the context management strategy

        - `class BetaInputTokensTrigger`

          - `type: :input_tokens`

            - `:input_tokens`

          - `value: Integer`

        - `class BetaToolUsesTrigger`

          - `type: :tool_uses`

            - `:tool_uses`

          - `value: Integer`

    - `class BetaClearThinking20251015Edit`

      - `type: :clear_thinking_20251015`

        - `:clear_thinking_20251015`

      - `keep: BetaThinkingTurns | BetaAllThinkingTurns | :all`

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        - `class BetaThinkingTurns`

          - `type: :thinking_turns`

            - `:thinking_turns`

          - `value: Integer`

        - `class BetaAllThinkingTurns`

          - `type: :all`

            - `:all`

        - `Keep = :all`

          - `:all`

    - `class BetaCompact20260112Edit`

      Automatically compact older context when reaching the configured trigger threshold.

      - `type: :compact_20260112`

        - `:compact_20260112`

      - `instructions: String`

        Additional instructions for summarization.

      - `pause_after_compaction: bool`

        Whether to pause after compaction and return the compaction block to the user.

      - `trigger: BetaInputTokensTrigger`

        When to trigger compaction. Defaults to 150000 input tokens.

- `mcp_servers: Array[BetaRequestMCPServerURLDefinition]`

  MCP servers to be utilized in this request

  - `name: String`

  - `type: :url`

    - `:url`

  - `url: String`

  - `authorization_token: String`

  - `tool_configuration: BetaRequestMCPServerToolConfiguration`

    - `allowed_tools: Array[String]`

    - `enabled: bool`

- `output_config: BetaOutputConfig`

  Configuration options for the model's output, such as the output format.

  - `effort: :low | :medium | :high | 2 more`

    All possible effort levels.

    - `:low`

    - `:medium`

    - `:high`

    - `:xhigh`

    - `:max`

  - `format_: BetaJSONOutputFormat`

    A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

    - `schema: Hash[Symbol, untyped]`

      The JSON schema of the format

    - `type: :json_schema`

      - `:json_schema`

  - `task_budget: BetaTokenTaskBudget`

    User-configurable total token budget across contexts.

    - `total: Integer`

      Total token budget across all contexts in the session.

    - `type: :tokens`

      The budget type. Currently only 'tokens' is supported.

      - `:tokens`

    - `remaining: Integer`

      Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

- `output_format: BetaJSONOutputFormat`

  Deprecated: Use `output_config.format` instead. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

  A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

- `speed: :standard | :fast`

  The inference speed mode for this request. `"fast"` enables high output-tokens-per-second inference.

  - `:standard`

  - `:fast`

- `system_: String | Array[BetaTextBlockParam]`

  System prompt.

  A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our [guide to system prompts](https://docs.claude.com/en/docs/system-prompts).

  - `String = String`

  - `UnionMember1 = Array[BetaTextBlockParam]`

    - `text: String`

    - `type: :text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: Array[BetaTextCitationParam]`

- `thinking: BetaThinkingConfigParam`

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include `thinking` content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your `max_tokens` limit.

  See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

  - `class BetaThinkingConfigEnabled`

    - `budget_tokens: Integer`

      Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

      Must be ≥1024 and less than `max_tokens`.

      See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

    - `type: :enabled`

      - `:enabled`

    - `display_: :summarized | :omitted`

      Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

      - `:summarized`

      - `:omitted`

  - `class BetaThinkingConfigDisabled`

    - `type: :disabled`

      - `:disabled`

  - `class BetaThinkingConfigAdaptive`

    - `type: :adaptive`

      - `:adaptive`

    - `display_: :summarized | :omitted`

      Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

      - `:summarized`

      - `:omitted`

- `tool_choice: BetaToolChoice`

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  - `class BetaToolChoiceAuto`

    The model will automatically decide whether to use tools.

    - `type: :auto`

      - `:auto`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output at most one tool use.

  - `class BetaToolChoiceAny`

    The model will use any available tools.

    - `type: :any`

      - `:any`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceTool`

    The model will use the specified tool with `tool_choice.name`.

    - `name: String`

      The name of the tool to use.

    - `type: :tool`

      - `:tool`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceNone`

    The model will not be allowed to use tools.

    - `type: :none`

      - `:none`

- `tools: Array[BetaTool | BetaToolBash20241022 | BetaToolBash20250124 | 20 more]`

  Definitions of tools that the model may use.

  If you include `tools` in your API request, the model may return `tool_use` content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using `tool_result` content blocks.

  There are two types of tools: **client tools** and **server tools**. The behavior described below applies to client tools. For [server tools](https://docs.claude.com/en/docs/agents-and-tools/tool-use/overview#server-tools), see their individual documentation as each has its own behavior (e.g., the [web search tool](https://docs.claude.com/en/docs/agents-and-tools/tool-use/web-search-tool)).

  Each tool definition includes:

  * `name`: Name of the tool.
  * `description`: Optional, but strongly-recommended description of the tool.
  * `input_schema`: [JSON schema](https://json-schema.org/draft/2020-12) for the tool `input` shape that the model will produce in `tool_use` output content blocks.

  For example, if you defined `tools` as:

  ```json
  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]
  ```

  And then asked the model "What's the S&P 500 at today?", the model might produce `tool_use` content blocks in the response like this:

  ```json
  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]
  ```

  You might then run your `get_stock_price` tool with `{"ticker": "^GSPC"}` as an input, and return the following back to the model in a subsequent `user` message:

  ```json
  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]
  ```

  Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

  See our [guide](https://docs.claude.com/en/docs/tool-use) for more details.

  - `class BetaTool`

    - `input_schema: InputSchema{ type, properties, required}`

      [JSON schema](https://json-schema.org/draft/2020-12) for this tool's input.

      This defines the shape of the `input` that your tool accepts and that the model will produce.

      - `type: :object`

        - `:object`

      - `properties: Hash[Symbol, untyped]`

      - `required: Array[String]`

    - `name: String`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `description: String`

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    - `eager_input_streaming: bool`

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `type: :custom`

      - `:custom`

  - `class BetaToolBash20241022`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20241022`

      - `:bash_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolBash20250124`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20250124`

      - `:bash_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250522`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250522`

      - `:code_execution_20250522`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250825`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250825`

      - `:code_execution_20250825`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20260120`

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20260120`

      - `:code_execution_20260120`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20241022`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20241022`

      - `:computer_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMemoryTool20250818`

    - `name: :memory`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:memory`

    - `type: :memory_20250818`

      - `:memory_20250818`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20250124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20250124`

      - `:computer_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20241022`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20241022`

      - `:text_editor_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20251124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20251124`

      - `:computer_20251124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `enable_zoom: bool`

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250124`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20250124`

      - `:text_editor_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250429`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250429`

      - `:text_editor_20250429`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250728`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250728`

      - `:text_editor_20250728`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `max_characters: Integer`

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20250305`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20250305`

      - `:web_search_20250305`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

      - `type: :approximate`

        - `:approximate`

      - `city: String`

        The city of the user.

      - `country: String`

        The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

      - `region: String`

        The region of the user.

      - `timezone: String`

        The [IANA timezone](https://nodatime.org/TimeZones) of the user.

  - `class BetaWebFetchTool20250910`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20250910`

      - `:web_fetch_20250910`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20260209`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20260209`

      - `:web_search_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

  - `class BetaWebFetchTool20260209`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260209`

      - `:web_fetch_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebFetchTool20260309`

    Web fetch tool with use_cache parameter for bypassing cached content.

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260309`

      - `:web_fetch_20260309`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `use_cache: bool`

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  - `class BetaAdvisorTool20260301`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `name: :advisor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:advisor`

    - `type: :advisor_20260301`

      - `:advisor_20260301`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caching: BetaCacheControlEphemeral`

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_tokens: Integer`

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolBm25_20251119`

    - `name: :tool_search_tool_bm25`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_bm25`

    - `type: :tool_search_tool_bm25_20251119 | :tool_search_tool_bm25`

      - `:tool_search_tool_bm25_20251119`

      - `:tool_search_tool_bm25`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolRegex20251119`

    - `name: :tool_search_tool_regex`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_regex`

    - `type: :tool_search_tool_regex_20251119 | :tool_search_tool_regex`

      - `:tool_search_tool_regex_20251119`

      - `:tool_search_tool_regex`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMCPToolset`

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools
    from an MCP server, with optional per-tool overrides.

    - `mcp_server_name: String`

      Name of the MCP server to configure tools for

    - `type: :mcp_toolset`

      - `:mcp_toolset`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `configs: Hash[Symbol, BetaMCPToolConfig]`

      Configuration overrides for specific tools, keyed by tool name

      - `defer_loading: bool`

      - `enabled: bool`

    - `default_config: BetaMCPToolDefaultConfig`

      Default configuration applied to all tools from this server

      - `defer_loading: bool`

      - `enabled: bool`

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageTokensCount`

  - `context_management: BetaCountTokensContextManagementResponse`

    Information about context management applied to the message.

    - `original_input_tokens: Integer`

      The original token count before context management was applied

  - `input_tokens: Integer`

    The total number of tokens across the provided list of messages, system prompt, and tools.

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message_tokens_count = anthropic.beta.messages.count_tokens(
  messages: [{content: "Hello, world", role: :user}],
  model: :"claude-opus-4-6"
)

puts(beta_message_tokens_count)
```

#### Response

```json
{
  "context_management": {
    "original_input_tokens": 0
  },
  "input_tokens": 2095
}
```

## Domain Types

### Beta Advisor Message Iteration Usage

- `class BetaAdvisorMessageIterationUsage`

  Token usage for an advisor sub-inference iteration.

  - `cache_creation: BetaCacheCreation`

    Breakdown of cached tokens by TTL

    - `ephemeral_1h_input_tokens: Integer`

      The number of input tokens used to create the 1 hour cache entry.

    - `ephemeral_5m_input_tokens: Integer`

      The number of input tokens used to create the 5 minute cache entry.

  - `cache_creation_input_tokens: Integer`

    The number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The number of input tokens read from the cache.

  - `input_tokens: Integer`

    The number of input tokens which were used.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

  - `output_tokens: Integer`

    The number of output tokens which were used.

  - `type: :advisor_message`

    Usage for an advisor sub-inference iteration

    - `:advisor_message`

### Beta Advisor Redacted Result Block

- `class BetaAdvisorRedactedResultBlock`

  - `encrypted_content: String`

    Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

  - `stop_reason: String`

    The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

  - `type: :advisor_redacted_result`

    - `:advisor_redacted_result`

### Beta Advisor Redacted Result Block Param

- `class BetaAdvisorRedactedResultBlockParam`

  - `encrypted_content: String`

    Opaque blob produced by a prior response; must be round-tripped verbatim.

  - `type: :advisor_redacted_result`

    - `:advisor_redacted_result`

  - `stop_reason: String`

### Beta Advisor Result Block

- `class BetaAdvisorResultBlock`

  - `stop_reason: String`

    The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

  - `text: String`

  - `type: :advisor_result`

    - `:advisor_result`

### Beta Advisor Result Block Param

- `class BetaAdvisorResultBlockParam`

  - `text: String`

  - `type: :advisor_result`

    - `:advisor_result`

  - `stop_reason: String`

### Beta Advisor Tool 20260301

- `class BetaAdvisorTool20260301`

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

  - `name: :advisor`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:advisor`

  - `type: :advisor_20260301`

    - `:advisor_20260301`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `caching: BetaCacheControlEphemeral`

    Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_tokens: Integer`

    Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Advisor Tool Result Block

- `class BetaAdvisorToolResultBlock`

  - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

    - `class BetaAdvisorToolResultError`

      - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

        - `:max_uses_exceeded`

        - `:prompt_too_long`

        - `:too_many_requests`

        - `:overloaded`

        - `:unavailable`

        - `:execution_time_exceeded`

        - `:model_not_found`

      - `type: :advisor_tool_result_error`

        - `:advisor_tool_result_error`

    - `class BetaAdvisorResultBlock`

      - `stop_reason: String`

        The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

      - `text: String`

      - `type: :advisor_result`

        - `:advisor_result`

    - `class BetaAdvisorRedactedResultBlock`

      - `encrypted_content: String`

        Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

      - `stop_reason: String`

        The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

      - `type: :advisor_redacted_result`

        - `:advisor_redacted_result`

  - `tool_use_id: String`

  - `type: :advisor_tool_result`

    - `:advisor_tool_result`

### Beta Advisor Tool Result Block Param

- `class BetaAdvisorToolResultBlockParam`

  - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

    - `class BetaAdvisorToolResultErrorParam`

      - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

        - `:max_uses_exceeded`

        - `:prompt_too_long`

        - `:too_many_requests`

        - `:overloaded`

        - `:unavailable`

        - `:execution_time_exceeded`

        - `:model_not_found`

      - `type: :advisor_tool_result_error`

        - `:advisor_tool_result_error`

    - `class BetaAdvisorResultBlockParam`

      - `text: String`

      - `type: :advisor_result`

        - `:advisor_result`

      - `stop_reason: String`

    - `class BetaAdvisorRedactedResultBlockParam`

      - `encrypted_content: String`

        Opaque blob produced by a prior response; must be round-tripped verbatim.

      - `type: :advisor_redacted_result`

        - `:advisor_redacted_result`

      - `stop_reason: String`

  - `tool_use_id: String`

  - `type: :advisor_tool_result`

    - `:advisor_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Advisor Tool Result Error

- `class BetaAdvisorToolResultError`

  - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

    - `:max_uses_exceeded`

    - `:prompt_too_long`

    - `:too_many_requests`

    - `:overloaded`

    - `:unavailable`

    - `:execution_time_exceeded`

    - `:model_not_found`

  - `type: :advisor_tool_result_error`

    - `:advisor_tool_result_error`

### Beta Advisor Tool Result Error Param

- `class BetaAdvisorToolResultErrorParam`

  - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

    - `:max_uses_exceeded`

    - `:prompt_too_long`

    - `:too_many_requests`

    - `:overloaded`

    - `:unavailable`

    - `:execution_time_exceeded`

    - `:model_not_found`

  - `type: :advisor_tool_result_error`

    - `:advisor_tool_result_error`

### Beta All Thinking Turns

- `class BetaAllThinkingTurns`

  - `type: :all`

    - `:all`

### Beta Base64 Image Source

- `class BetaBase64ImageSource`

  - `data: String`

  - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

    - `:"image/jpeg"`

    - `:"image/png"`

    - `:"image/gif"`

    - `:"image/webp"`

  - `type: :base64`

    - `:base64`

### Beta Base64 PDF Source

- `class BetaBase64PDFSource`

  - `data: String`

  - `media_type: :"application/pdf"`

    - `:"application/pdf"`

  - `type: :base64`

    - `:base64`

### Beta Bash Code Execution Output Block

- `class BetaBashCodeExecutionOutputBlock`

  - `file_id: String`

  - `type: :bash_code_execution_output`

    - `:bash_code_execution_output`

### Beta Bash Code Execution Output Block Param

- `class BetaBashCodeExecutionOutputBlockParam`

  - `file_id: String`

  - `type: :bash_code_execution_output`

    - `:bash_code_execution_output`

### Beta Bash Code Execution Result Block

- `class BetaBashCodeExecutionResultBlock`

  - `content: Array[BetaBashCodeExecutionOutputBlock]`

    - `file_id: String`

    - `type: :bash_code_execution_output`

      - `:bash_code_execution_output`

  - `return_code: Integer`

  - `stderr: String`

  - `stdout: String`

  - `type: :bash_code_execution_result`

    - `:bash_code_execution_result`

### Beta Bash Code Execution Result Block Param

- `class BetaBashCodeExecutionResultBlockParam`

  - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

    - `file_id: String`

    - `type: :bash_code_execution_output`

      - `:bash_code_execution_output`

  - `return_code: Integer`

  - `stderr: String`

  - `stdout: String`

  - `type: :bash_code_execution_result`

    - `:bash_code_execution_result`

### Beta Bash Code Execution Tool Result Block

- `class BetaBashCodeExecutionToolResultBlock`

  - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

    - `class BetaBashCodeExecutionToolResultError`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

        - `:output_file_too_large`

      - `type: :bash_code_execution_tool_result_error`

        - `:bash_code_execution_tool_result_error`

    - `class BetaBashCodeExecutionResultBlock`

      - `content: Array[BetaBashCodeExecutionOutputBlock]`

        - `file_id: String`

        - `type: :bash_code_execution_output`

          - `:bash_code_execution_output`

      - `return_code: Integer`

      - `stderr: String`

      - `stdout: String`

      - `type: :bash_code_execution_result`

        - `:bash_code_execution_result`

  - `tool_use_id: String`

  - `type: :bash_code_execution_tool_result`

    - `:bash_code_execution_tool_result`

### Beta Bash Code Execution Tool Result Block Param

- `class BetaBashCodeExecutionToolResultBlockParam`

  - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

    - `class BetaBashCodeExecutionToolResultErrorParam`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

        - `:output_file_too_large`

      - `type: :bash_code_execution_tool_result_error`

        - `:bash_code_execution_tool_result_error`

    - `class BetaBashCodeExecutionResultBlockParam`

      - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

        - `file_id: String`

        - `type: :bash_code_execution_output`

          - `:bash_code_execution_output`

      - `return_code: Integer`

      - `stderr: String`

      - `stdout: String`

      - `type: :bash_code_execution_result`

        - `:bash_code_execution_result`

  - `tool_use_id: String`

  - `type: :bash_code_execution_tool_result`

    - `:bash_code_execution_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Bash Code Execution Tool Result Error

- `class BetaBashCodeExecutionToolResultError`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

    - `:output_file_too_large`

  - `type: :bash_code_execution_tool_result_error`

    - `:bash_code_execution_tool_result_error`

### Beta Bash Code Execution Tool Result Error Param

- `class BetaBashCodeExecutionToolResultErrorParam`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

    - `:output_file_too_large`

  - `type: :bash_code_execution_tool_result_error`

    - `:bash_code_execution_tool_result_error`

### Beta Cache Control Ephemeral

- `class BetaCacheControlEphemeral`

  - `type: :ephemeral`

    - `:ephemeral`

  - `ttl: :"5m" | :"1h"`

    The time-to-live for the cache control breakpoint.

    This may be one the following values:

    - `5m`: 5 minutes
    - `1h`: 1 hour

    Defaults to `5m`.

    - `:"5m"`

    - `:"1h"`

### Beta Cache Creation

- `class BetaCacheCreation`

  - `ephemeral_1h_input_tokens: Integer`

    The number of input tokens used to create the 1 hour cache entry.

  - `ephemeral_5m_input_tokens: Integer`

    The number of input tokens used to create the 5 minute cache entry.

### Beta Cache Miss Messages Changed

- `class BetaCacheMissMessagesChanged`

  - `cache_missed_input_tokens: Integer`

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

  - `type: :messages_changed`

    - `:messages_changed`

### Beta Cache Miss Model Changed

- `class BetaCacheMissModelChanged`

  - `cache_missed_input_tokens: Integer`

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

  - `type: :model_changed`

    - `:model_changed`

### Beta Cache Miss Previous Message Not Found

- `class BetaCacheMissPreviousMessageNotFound`

  - `type: :previous_message_not_found`

    - `:previous_message_not_found`

### Beta Cache Miss System Changed

- `class BetaCacheMissSystemChanged`

  - `cache_missed_input_tokens: Integer`

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

  - `type: :system_changed`

    - `:system_changed`

### Beta Cache Miss Tools Changed

- `class BetaCacheMissToolsChanged`

  - `cache_missed_input_tokens: Integer`

    Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

  - `type: :tools_changed`

    - `:tools_changed`

### Beta Cache Miss Unavailable

- `class BetaCacheMissUnavailable`

  - `type: :unavailable`

    - `:unavailable`

### Beta Citation Char Location

- `class BetaCitationCharLocation`

  - `cited_text: String`

  - `document_index: Integer`

  - `document_title: String`

  - `end_char_index: Integer`

  - `file_id: String`

  - `start_char_index: Integer`

  - `type: :char_location`

    - `:char_location`

### Beta Citation Char Location Param

- `class BetaCitationCharLocationParam`

  - `cited_text: String`

  - `document_index: Integer`

  - `document_title: String`

  - `end_char_index: Integer`

  - `start_char_index: Integer`

  - `type: :char_location`

    - `:char_location`

### Beta Citation Config

- `class BetaCitationConfig`

  - `enabled: bool`

### Beta Citation Content Block Location

- `class BetaCitationContentBlockLocation`

  - `cited_text: String`

    The full text of the cited block range, concatenated.

    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  - `document_index: Integer`

  - `document_title: String`

  - `end_block_index: Integer`

    Exclusive 0-based end index of the cited block range in the source's `content` array.

    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

  - `file_id: String`

  - `start_block_index: Integer`

    0-based index of the first cited block in the source's `content` array.

  - `type: :content_block_location`

    - `:content_block_location`

### Beta Citation Content Block Location Param

- `class BetaCitationContentBlockLocationParam`

  - `cited_text: String`

    The full text of the cited block range, concatenated.

    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  - `document_index: Integer`

  - `document_title: String`

  - `end_block_index: Integer`

    Exclusive 0-based end index of the cited block range in the source's `content` array.

    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

  - `start_block_index: Integer`

    0-based index of the first cited block in the source's `content` array.

  - `type: :content_block_location`

    - `:content_block_location`

### Beta Citation Page Location

- `class BetaCitationPageLocation`

  - `cited_text: String`

  - `document_index: Integer`

  - `document_title: String`

  - `end_page_number: Integer`

  - `file_id: String`

  - `start_page_number: Integer`

  - `type: :page_location`

    - `:page_location`

### Beta Citation Page Location Param

- `class BetaCitationPageLocationParam`

  - `cited_text: String`

  - `document_index: Integer`

  - `document_title: String`

  - `end_page_number: Integer`

  - `start_page_number: Integer`

  - `type: :page_location`

    - `:page_location`

### Beta Citation Search Result Location

- `class BetaCitationSearchResultLocation`

  - `cited_text: String`

    The full text of the cited block range, concatenated.

    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  - `end_block_index: Integer`

    Exclusive 0-based end index of the cited block range in the source's `content` array.

    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

  - `search_result_index: Integer`

    0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

    Counted separately from `document_index`; server-side web search results are not included in this count.

  - `source: String`

  - `start_block_index: Integer`

    0-based index of the first cited block in the source's `content` array.

  - `title: String`

  - `type: :search_result_location`

    - `:search_result_location`

### Beta Citation Search Result Location Param

- `class BetaCitationSearchResultLocationParam`

  - `cited_text: String`

    The full text of the cited block range, concatenated.

    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

  - `end_block_index: Integer`

    Exclusive 0-based end index of the cited block range in the source's `content` array.

    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

  - `search_result_index: Integer`

    0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

    Counted separately from `document_index`; server-side web search results are not included in this count.

  - `source: String`

  - `start_block_index: Integer`

    0-based index of the first cited block in the source's `content` array.

  - `title: String`

  - `type: :search_result_location`

    - `:search_result_location`

### Beta Citation Web Search Result Location Param

- `class BetaCitationWebSearchResultLocationParam`

  - `cited_text: String`

  - `encrypted_index: String`

  - `title: String`

  - `type: :web_search_result_location`

    - `:web_search_result_location`

  - `url: String`

### Beta Citations Config Param

- `class BetaCitationsConfigParam`

  - `enabled: bool`

### Beta Citations Delta

- `class BetaCitationsDelta`

  - `citation: BetaCitationCharLocation | BetaCitationPageLocation | BetaCitationContentBlockLocation | 2 more`

    - `class BetaCitationCharLocation`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_char_index: Integer`

      - `file_id: String`

      - `start_char_index: Integer`

      - `type: :char_location`

        - `:char_location`

    - `class BetaCitationPageLocation`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_page_number: Integer`

      - `file_id: String`

      - `start_page_number: Integer`

      - `type: :page_location`

        - `:page_location`

    - `class BetaCitationContentBlockLocation`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `document_index: Integer`

      - `document_title: String`

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `file_id: String`

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `type: :content_block_location`

        - `:content_block_location`

    - `class BetaCitationsWebSearchResultLocation`

      - `cited_text: String`

      - `encrypted_index: String`

      - `title: String`

      - `type: :web_search_result_location`

        - `:web_search_result_location`

      - `url: String`

    - `class BetaCitationSearchResultLocation`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `search_result_index: Integer`

        0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from `document_index`; server-side web search results are not included in this count.

      - `source: String`

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `title: String`

      - `type: :search_result_location`

        - `:search_result_location`

  - `type: :citations_delta`

    - `:citations_delta`

### Beta Citations Web Search Result Location

- `class BetaCitationsWebSearchResultLocation`

  - `cited_text: String`

  - `encrypted_index: String`

  - `title: String`

  - `type: :web_search_result_location`

    - `:web_search_result_location`

  - `url: String`

### Beta Clear Thinking 20251015 Edit

- `class BetaClearThinking20251015Edit`

  - `type: :clear_thinking_20251015`

    - `:clear_thinking_20251015`

  - `keep: BetaThinkingTurns | BetaAllThinkingTurns | :all`

    Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

    - `class BetaThinkingTurns`

      - `type: :thinking_turns`

        - `:thinking_turns`

      - `value: Integer`

    - `class BetaAllThinkingTurns`

      - `type: :all`

        - `:all`

    - `Keep = :all`

      - `:all`

### Beta Clear Thinking 20251015 Edit Response

- `class BetaClearThinking20251015EditResponse`

  - `cleared_input_tokens: Integer`

    Number of input tokens cleared by this edit.

  - `cleared_thinking_turns: Integer`

    Number of thinking turns that were cleared.

  - `type: :clear_thinking_20251015`

    The type of context management edit applied.

    - `:clear_thinking_20251015`

### Beta Clear Tool Uses 20250919 Edit

- `class BetaClearToolUses20250919Edit`

  - `type: :clear_tool_uses_20250919`

    - `:clear_tool_uses_20250919`

  - `clear_at_least: BetaInputTokensClearAtLeast`

    Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

    - `type: :input_tokens`

      - `:input_tokens`

    - `value: Integer`

  - `clear_tool_inputs: bool | Array[String]`

    Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

    - `UnionMember0 = bool`

    - `UnionMember1 = Array[String]`

  - `exclude_tools: Array[String]`

    Tool names whose uses are preserved from clearing

  - `keep: BetaToolUsesKeep`

    Number of tool uses to retain in the conversation

    - `type: :tool_uses`

      - `:tool_uses`

    - `value: Integer`

  - `trigger: BetaInputTokensTrigger | BetaToolUsesTrigger`

    Condition that triggers the context management strategy

    - `class BetaInputTokensTrigger`

      - `type: :input_tokens`

        - `:input_tokens`

      - `value: Integer`

    - `class BetaToolUsesTrigger`

      - `type: :tool_uses`

        - `:tool_uses`

      - `value: Integer`

### Beta Clear Tool Uses 20250919 Edit Response

- `class BetaClearToolUses20250919EditResponse`

  - `cleared_input_tokens: Integer`

    Number of input tokens cleared by this edit.

  - `cleared_tool_uses: Integer`

    Number of tool uses that were cleared.

  - `type: :clear_tool_uses_20250919`

    The type of context management edit applied.

    - `:clear_tool_uses_20250919`

### Beta Code Execution Output Block

- `class BetaCodeExecutionOutputBlock`

  - `file_id: String`

  - `type: :code_execution_output`

    - `:code_execution_output`

### Beta Code Execution Output Block Param

- `class BetaCodeExecutionOutputBlockParam`

  - `file_id: String`

  - `type: :code_execution_output`

    - `:code_execution_output`

### Beta Code Execution Result Block

- `class BetaCodeExecutionResultBlock`

  - `content: Array[BetaCodeExecutionOutputBlock]`

    - `file_id: String`

    - `type: :code_execution_output`

      - `:code_execution_output`

  - `return_code: Integer`

  - `stderr: String`

  - `stdout: String`

  - `type: :code_execution_result`

    - `:code_execution_result`

### Beta Code Execution Result Block Param

- `class BetaCodeExecutionResultBlockParam`

  - `content: Array[BetaCodeExecutionOutputBlockParam]`

    - `file_id: String`

    - `type: :code_execution_output`

      - `:code_execution_output`

  - `return_code: Integer`

  - `stderr: String`

  - `stdout: String`

  - `type: :code_execution_result`

    - `:code_execution_result`

### Beta Code Execution Tool 20250522

- `class BetaCodeExecutionTool20250522`

  - `name: :code_execution`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:code_execution`

  - `type: :code_execution_20250522`

    - `:code_execution_20250522`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Code Execution Tool 20250825

- `class BetaCodeExecutionTool20250825`

  - `name: :code_execution`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:code_execution`

  - `type: :code_execution_20250825`

    - `:code_execution_20250825`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Code Execution Tool 20260120

- `class BetaCodeExecutionTool20260120`

  Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

  - `name: :code_execution`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:code_execution`

  - `type: :code_execution_20260120`

    - `:code_execution_20260120`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Code Execution Tool Result Block

- `class BetaCodeExecutionToolResultBlock`

  - `content: BetaCodeExecutionToolResultBlockContent`

    Code execution result with encrypted stdout for PFC + web_search results.

    - `class BetaCodeExecutionToolResultError`

      - `error_code: BetaCodeExecutionToolResultErrorCode`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

      - `type: :code_execution_tool_result_error`

        - `:code_execution_tool_result_error`

    - `class BetaCodeExecutionResultBlock`

      - `content: Array[BetaCodeExecutionOutputBlock]`

        - `file_id: String`

        - `type: :code_execution_output`

          - `:code_execution_output`

      - `return_code: Integer`

      - `stderr: String`

      - `stdout: String`

      - `type: :code_execution_result`

        - `:code_execution_result`

    - `class BetaEncryptedCodeExecutionResultBlock`

      Code execution result with encrypted stdout for PFC + web_search results.

      - `content: Array[BetaCodeExecutionOutputBlock]`

        - `file_id: String`

        - `type: :code_execution_output`

      - `encrypted_stdout: String`

      - `return_code: Integer`

      - `stderr: String`

      - `type: :encrypted_code_execution_result`

        - `:encrypted_code_execution_result`

  - `tool_use_id: String`

  - `type: :code_execution_tool_result`

    - `:code_execution_tool_result`

### Beta Code Execution Tool Result Block Content

- `BetaCodeExecutionToolResultBlockContent = BetaCodeExecutionToolResultError | BetaCodeExecutionResultBlock | BetaEncryptedCodeExecutionResultBlock`

  Code execution result with encrypted stdout for PFC + web_search results.

  - `class BetaCodeExecutionToolResultError`

    - `error_code: BetaCodeExecutionToolResultErrorCode`

      - `:invalid_tool_input`

      - `:unavailable`

      - `:too_many_requests`

      - `:execution_time_exceeded`

    - `type: :code_execution_tool_result_error`

      - `:code_execution_tool_result_error`

  - `class BetaCodeExecutionResultBlock`

    - `content: Array[BetaCodeExecutionOutputBlock]`

      - `file_id: String`

      - `type: :code_execution_output`

        - `:code_execution_output`

    - `return_code: Integer`

    - `stderr: String`

    - `stdout: String`

    - `type: :code_execution_result`

      - `:code_execution_result`

  - `class BetaEncryptedCodeExecutionResultBlock`

    Code execution result with encrypted stdout for PFC + web_search results.

    - `content: Array[BetaCodeExecutionOutputBlock]`

      - `file_id: String`

      - `type: :code_execution_output`

    - `encrypted_stdout: String`

    - `return_code: Integer`

    - `stderr: String`

    - `type: :encrypted_code_execution_result`

      - `:encrypted_code_execution_result`

### Beta Code Execution Tool Result Block Param

- `class BetaCodeExecutionToolResultBlockParam`

  - `content: BetaCodeExecutionToolResultBlockParamContent`

    Code execution result with encrypted stdout for PFC + web_search results.

    - `class BetaCodeExecutionToolResultErrorParam`

      - `error_code: BetaCodeExecutionToolResultErrorCode`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

      - `type: :code_execution_tool_result_error`

        - `:code_execution_tool_result_error`

    - `class BetaCodeExecutionResultBlockParam`

      - `content: Array[BetaCodeExecutionOutputBlockParam]`

        - `file_id: String`

        - `type: :code_execution_output`

          - `:code_execution_output`

      - `return_code: Integer`

      - `stderr: String`

      - `stdout: String`

      - `type: :code_execution_result`

        - `:code_execution_result`

    - `class BetaEncryptedCodeExecutionResultBlockParam`

      Code execution result with encrypted stdout for PFC + web_search results.

      - `content: Array[BetaCodeExecutionOutputBlockParam]`

        - `file_id: String`

        - `type: :code_execution_output`

      - `encrypted_stdout: String`

      - `return_code: Integer`

      - `stderr: String`

      - `type: :encrypted_code_execution_result`

        - `:encrypted_code_execution_result`

  - `tool_use_id: String`

  - `type: :code_execution_tool_result`

    - `:code_execution_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Code Execution Tool Result Block Param Content

- `BetaCodeExecutionToolResultBlockParamContent = BetaCodeExecutionToolResultErrorParam | BetaCodeExecutionResultBlockParam | BetaEncryptedCodeExecutionResultBlockParam`

  Code execution result with encrypted stdout for PFC + web_search results.

  - `class BetaCodeExecutionToolResultErrorParam`

    - `error_code: BetaCodeExecutionToolResultErrorCode`

      - `:invalid_tool_input`

      - `:unavailable`

      - `:too_many_requests`

      - `:execution_time_exceeded`

    - `type: :code_execution_tool_result_error`

      - `:code_execution_tool_result_error`

  - `class BetaCodeExecutionResultBlockParam`

    - `content: Array[BetaCodeExecutionOutputBlockParam]`

      - `file_id: String`

      - `type: :code_execution_output`

        - `:code_execution_output`

    - `return_code: Integer`

    - `stderr: String`

    - `stdout: String`

    - `type: :code_execution_result`

      - `:code_execution_result`

  - `class BetaEncryptedCodeExecutionResultBlockParam`

    Code execution result with encrypted stdout for PFC + web_search results.

    - `content: Array[BetaCodeExecutionOutputBlockParam]`

      - `file_id: String`

      - `type: :code_execution_output`

    - `encrypted_stdout: String`

    - `return_code: Integer`

    - `stderr: String`

    - `type: :encrypted_code_execution_result`

      - `:encrypted_code_execution_result`

### Beta Code Execution Tool Result Error

- `class BetaCodeExecutionToolResultError`

  - `error_code: BetaCodeExecutionToolResultErrorCode`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

  - `type: :code_execution_tool_result_error`

    - `:code_execution_tool_result_error`

### Beta Code Execution Tool Result Error Code

- `BetaCodeExecutionToolResultErrorCode = :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

  - `:invalid_tool_input`

  - `:unavailable`

  - `:too_many_requests`

  - `:execution_time_exceeded`

### Beta Code Execution Tool Result Error Param

- `class BetaCodeExecutionToolResultErrorParam`

  - `error_code: BetaCodeExecutionToolResultErrorCode`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

  - `type: :code_execution_tool_result_error`

    - `:code_execution_tool_result_error`

### Beta Compact 20260112 Edit

- `class BetaCompact20260112Edit`

  Automatically compact older context when reaching the configured trigger threshold.

  - `type: :compact_20260112`

    - `:compact_20260112`

  - `instructions: String`

    Additional instructions for summarization.

  - `pause_after_compaction: bool`

    Whether to pause after compaction and return the compaction block to the user.

  - `trigger: BetaInputTokensTrigger`

    When to trigger compaction. Defaults to 150000 input tokens.

    - `type: :input_tokens`

      - `:input_tokens`

    - `value: Integer`

### Beta Compaction Block

- `class BetaCompactionBlock`

  A compaction block returned when autocompact is triggered.

  When content is None, it indicates the compaction failed to produce a valid
  summary (e.g., malformed output from the model). Clients may round-trip
  compaction blocks with null content; the server treats them as no-ops.

  - `content: String`

    Summary of compacted content, or null if compaction failed

  - `encrypted_content: String`

    Opaque metadata from prior compaction, to be round-tripped verbatim

  - `type: :compaction`

    - `:compaction`

### Beta Compaction Block Param

- `class BetaCompactionBlockParam`

  A compaction block containing summary of previous context.

  Users should round-trip these blocks from responses to subsequent requests
  to maintain context across compaction boundaries.

  When content is None, the block represents a failed compaction. The server
  treats these as no-ops. Empty string content is not allowed.

  - `type: :compaction`

    - `:compaction`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `content: String`

    Summary of previously compacted content, or null if compaction failed

  - `encrypted_content: String`

    Opaque metadata from prior compaction, to be round-tripped verbatim

### Beta Compaction Content Block Delta

- `class BetaCompactionContentBlockDelta`

  - `content: String`

  - `encrypted_content: String`

    Opaque metadata from prior compaction, to be round-tripped verbatim

  - `type: :compaction_delta`

    - `:compaction_delta`

### Beta Compaction Iteration Usage

- `class BetaCompactionIterationUsage`

  Token usage for a compaction iteration.

  - `cache_creation: BetaCacheCreation`

    Breakdown of cached tokens by TTL

    - `ephemeral_1h_input_tokens: Integer`

      The number of input tokens used to create the 1 hour cache entry.

    - `ephemeral_5m_input_tokens: Integer`

      The number of input tokens used to create the 5 minute cache entry.

  - `cache_creation_input_tokens: Integer`

    The number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The number of input tokens read from the cache.

  - `input_tokens: Integer`

    The number of input tokens which were used.

  - `output_tokens: Integer`

    The number of output tokens which were used.

  - `type: :compaction`

    Usage for a compaction iteration

    - `:compaction`

### Beta Container

- `class BetaContainer`

  Information about the container used in the request (for the code execution tool)

  - `id: String`

    Identifier for the container used in this request

  - `expires_at: Time`

    The time at which the container will expire.

  - `skills: Array[BetaSkill]`

    Skills loaded in the container

    - `skill_id: String`

      Skill ID

    - `type: :anthropic | :custom`

      Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

      - `:anthropic`

      - `:custom`

    - `version: String`

      Skill version or 'latest' for most recent version

### Beta Container Params

- `class BetaContainerParams`

  Container parameters with skills to be loaded.

  - `id: String`

    Container id

  - `skills: Array[BetaSkillParams]`

    List of skills to load in the container

    - `skill_id: String`

      Skill ID

    - `type: :anthropic | :custom`

      Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

      - `:anthropic`

      - `:custom`

    - `version: String`

      Skill version or 'latest' for most recent version

### Beta Container Upload Block

- `class BetaContainerUploadBlock`

  Response model for a file uploaded to the container.

  - `file_id: String`

  - `type: :container_upload`

    - `:container_upload`

### Beta Container Upload Block Param

- `class BetaContainerUploadBlockParam`

  A content block that represents a file to be uploaded to the container
  Files uploaded via this block will be available in the container's input directory.

  - `file_id: String`

  - `type: :container_upload`

    - `:container_upload`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Content Block

- `BetaContentBlock = BetaTextBlock | BetaThinkingBlock | BetaRedactedThinkingBlock | 14 more`

  Response model for a file uploaded to the container.

  - `class BetaTextBlock`

    - `citations: Array[BetaTextCitation]`

      Citations supporting the text block.

      The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

      - `class BetaCitationCharLocation`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `file_id: String`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocation`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `file_id: String`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocation`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `file_id: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationsWebSearchResultLocation`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocation`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

    - `text: String`

    - `type: :text`

      - `:text`

  - `class BetaThinkingBlock`

    - `signature: String`

    - `thinking: String`

    - `type: :thinking`

      - `:thinking`

  - `class BetaRedactedThinkingBlock`

    - `data: String`

    - `type: :redacted_thinking`

      - `:redacted_thinking`

  - `class BetaToolUseBlock`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: String`

    - `type: :tool_use`

      - `:tool_use`

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

        - `type: :direct`

          - `:direct`

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

        - `tool_id: String`

        - `type: :code_execution_20250825`

          - `:code_execution_20250825`

      - `class BetaServerToolCaller20260120`

        - `tool_id: String`

        - `type: :code_execution_20260120`

          - `:code_execution_20260120`

  - `class BetaServerToolUseBlock`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: :advisor | :web_search | :web_fetch | 5 more`

      - `:advisor`

      - `:web_search`

      - `:web_fetch`

      - `:code_execution`

      - `:bash_code_execution`

      - `:text_editor_code_execution`

      - `:tool_search_tool_regex`

      - `:tool_search_tool_bm25`

    - `type: :server_tool_use`

      - `:server_tool_use`

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaWebSearchToolResultBlock`

    - `content: BetaWebSearchToolResultBlockContent`

      - `class BetaWebSearchToolResultError`

        - `error_code: BetaWebSearchToolResultErrorCode`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:max_uses_exceeded`

          - `:too_many_requests`

          - `:query_too_long`

          - `:request_too_large`

        - `type: :web_search_tool_result_error`

          - `:web_search_tool_result_error`

      - `UnionMember1 = Array[BetaWebSearchResultBlock]`

        - `encrypted_content: String`

        - `page_age: String`

        - `title: String`

        - `type: :web_search_result`

          - `:web_search_result`

        - `url: String`

    - `tool_use_id: String`

    - `type: :web_search_tool_result`

      - `:web_search_tool_result`

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaWebFetchToolResultBlock`

    - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

      - `class BetaWebFetchToolResultErrorBlock`

        - `error_code: BetaWebFetchToolResultErrorCode`

          - `:invalid_tool_input`

          - `:url_too_long`

          - `:url_not_allowed`

          - `:url_not_in_prior_context`

          - `:url_not_accessible`

          - `:unsupported_content_type`

          - `:too_many_requests`

          - `:max_uses_exceeded`

          - `:unavailable`

        - `type: :web_fetch_tool_result_error`

          - `:web_fetch_tool_result_error`

      - `class BetaWebFetchBlock`

        - `content: BetaDocumentBlock`

          - `citations: BetaCitationConfig`

            Citation configuration for the document

            - `enabled: bool`

          - `source: BetaBase64PDFSource | BetaPlainTextSource`

            - `class BetaBase64PDFSource`

              - `data: String`

              - `media_type: :"application/pdf"`

                - `:"application/pdf"`

              - `type: :base64`

                - `:base64`

            - `class BetaPlainTextSource`

              - `data: String`

              - `media_type: :"text/plain"`

                - `:"text/plain"`

              - `type: :text`

                - `:text`

          - `title: String`

            The title of the document

          - `type: :document`

            - `:document`

        - `retrieved_at: String`

          ISO 8601 timestamp when the content was retrieved

        - `type: :web_fetch_result`

          - `:web_fetch_result`

        - `url: String`

          Fetched content URL

    - `tool_use_id: String`

    - `type: :web_fetch_tool_result`

      - `:web_fetch_tool_result`

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaAdvisorToolResultBlock`

    - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

      - `class BetaAdvisorToolResultError`

        - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

          - `:max_uses_exceeded`

          - `:prompt_too_long`

          - `:too_many_requests`

          - `:overloaded`

          - `:unavailable`

          - `:execution_time_exceeded`

          - `:model_not_found`

        - `type: :advisor_tool_result_error`

          - `:advisor_tool_result_error`

      - `class BetaAdvisorResultBlock`

        - `stop_reason: String`

          The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

        - `text: String`

        - `type: :advisor_result`

          - `:advisor_result`

      - `class BetaAdvisorRedactedResultBlock`

        - `encrypted_content: String`

          Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

        - `stop_reason: String`

          The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

        - `type: :advisor_redacted_result`

          - `:advisor_redacted_result`

    - `tool_use_id: String`

    - `type: :advisor_tool_result`

      - `:advisor_tool_result`

  - `class BetaCodeExecutionToolResultBlock`

    - `content: BetaCodeExecutionToolResultBlockContent`

      Code execution result with encrypted stdout for PFC + web_search results.

      - `class BetaCodeExecutionToolResultError`

        - `error_code: BetaCodeExecutionToolResultErrorCode`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

        - `type: :code_execution_tool_result_error`

          - `:code_execution_tool_result_error`

      - `class BetaCodeExecutionResultBlock`

        - `content: Array[BetaCodeExecutionOutputBlock]`

          - `file_id: String`

          - `type: :code_execution_output`

            - `:code_execution_output`

        - `return_code: Integer`

        - `stderr: String`

        - `stdout: String`

        - `type: :code_execution_result`

          - `:code_execution_result`

      - `class BetaEncryptedCodeExecutionResultBlock`

        Code execution result with encrypted stdout for PFC + web_search results.

        - `content: Array[BetaCodeExecutionOutputBlock]`

          - `file_id: String`

          - `type: :code_execution_output`

        - `encrypted_stdout: String`

        - `return_code: Integer`

        - `stderr: String`

        - `type: :encrypted_code_execution_result`

          - `:encrypted_code_execution_result`

    - `tool_use_id: String`

    - `type: :code_execution_tool_result`

      - `:code_execution_tool_result`

  - `class BetaBashCodeExecutionToolResultBlock`

    - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

      - `class BetaBashCodeExecutionToolResultError`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

          - `:output_file_too_large`

        - `type: :bash_code_execution_tool_result_error`

          - `:bash_code_execution_tool_result_error`

      - `class BetaBashCodeExecutionResultBlock`

        - `content: Array[BetaBashCodeExecutionOutputBlock]`

          - `file_id: String`

          - `type: :bash_code_execution_output`

            - `:bash_code_execution_output`

        - `return_code: Integer`

        - `stderr: String`

        - `stdout: String`

        - `type: :bash_code_execution_result`

          - `:bash_code_execution_result`

    - `tool_use_id: String`

    - `type: :bash_code_execution_tool_result`

      - `:bash_code_execution_tool_result`

  - `class BetaTextEditorCodeExecutionToolResultBlock`

    - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

      - `class BetaTextEditorCodeExecutionToolResultError`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

          - `:file_not_found`

        - `error_message: String`

        - `type: :text_editor_code_execution_tool_result_error`

          - `:text_editor_code_execution_tool_result_error`

      - `class BetaTextEditorCodeExecutionViewResultBlock`

        - `content: String`

        - `file_type: :text | :image | :pdf`

          - `:text`

          - `:image`

          - `:pdf`

        - `num_lines: Integer`

        - `start_line: Integer`

        - `total_lines: Integer`

        - `type: :text_editor_code_execution_view_result`

          - `:text_editor_code_execution_view_result`

      - `class BetaTextEditorCodeExecutionCreateResultBlock`

        - `is_file_update: bool`

        - `type: :text_editor_code_execution_create_result`

          - `:text_editor_code_execution_create_result`

      - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

        - `lines: Array[String]`

        - `new_lines: Integer`

        - `new_start: Integer`

        - `old_lines: Integer`

        - `old_start: Integer`

        - `type: :text_editor_code_execution_str_replace_result`

          - `:text_editor_code_execution_str_replace_result`

    - `tool_use_id: String`

    - `type: :text_editor_code_execution_tool_result`

      - `:text_editor_code_execution_tool_result`

  - `class BetaToolSearchToolResultBlock`

    - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

      - `class BetaToolSearchToolResultError`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

        - `error_message: String`

        - `type: :tool_search_tool_result_error`

          - `:tool_search_tool_result_error`

      - `class BetaToolSearchToolSearchResultBlock`

        - `tool_references: Array[BetaToolReferenceBlock]`

          - `tool_name: String`

          - `type: :tool_reference`

            - `:tool_reference`

        - `type: :tool_search_tool_search_result`

          - `:tool_search_tool_search_result`

    - `tool_use_id: String`

    - `type: :tool_search_tool_result`

      - `:tool_search_tool_result`

  - `class BetaMCPToolUseBlock`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: String`

      The name of the MCP tool

    - `server_name: String`

      The name of the MCP server

    - `type: :mcp_tool_use`

      - `:mcp_tool_use`

  - `class BetaMCPToolResultBlock`

    - `content: String | Array[BetaTextBlock]`

      - `String = String`

      - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

        - `citations: Array[BetaTextCitation]`

          Citations supporting the text block.

          The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

        - `text: String`

        - `type: :text`

    - `is_error: bool`

    - `tool_use_id: String`

    - `type: :mcp_tool_result`

      - `:mcp_tool_result`

  - `class BetaContainerUploadBlock`

    Response model for a file uploaded to the container.

    - `file_id: String`

    - `type: :container_upload`

      - `:container_upload`

  - `class BetaCompactionBlock`

    A compaction block returned when autocompact is triggered.

    When content is None, it indicates the compaction failed to produce a valid
    summary (e.g., malformed output from the model). Clients may round-trip
    compaction blocks with null content; the server treats them as no-ops.

    - `content: String`

      Summary of compacted content, or null if compaction failed

    - `encrypted_content: String`

      Opaque metadata from prior compaction, to be round-tripped verbatim

    - `type: :compaction`

      - `:compaction`

  - `class BetaFallbackBlock`

    Marks the point in `content` where one model's output gives way to the next.

    One block appears per hop where a preceding model actually ran this turn and
    declined. A turn routed directly by the sticky decision has no such boundary
    and carries no block — the signal for whether a fallback model served the
    response is the presence of a `fallback_message` entry in
    `usage.iterations`, not this block.

    The block is treated like a server-tool content block for streaming: it
    arrives via the standard `content_block_start` / `content_block_stop`
    pair and carries no deltas.

    - `from: BetaFallbackInfo`

      The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `:"claude-fable-5"`

            Next generation of intelligence for the hardest knowledge work and coding problems

          - `:"claude-mythos-5"`

            Most capable model for cybersecurity and biology research

          - `:"claude-opus-4-8"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-opus-4-7"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-mythos-preview"`

            New class of intelligence, strongest in coding and cybersecurity

          - `:"claude-opus-4-6"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-sonnet-4-6"`

            Best combination of speed and intelligence

          - `:"claude-haiku-4-5"`

            Fastest model with near-frontier intelligence

          - `:"claude-haiku-4-5-20251001"`

            Fastest model with near-frontier intelligence

          - `:"claude-opus-4-5"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-opus-4-5-20251101"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-sonnet-4-5"`

            High-performance model for agents and coding

          - `:"claude-sonnet-4-5-20250929"`

            High-performance model for agents and coding

          - `:"claude-opus-4-1"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-1-20250805"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-0"`

            Powerful model for complex tasks

          - `:"claude-opus-4-20250514"`

            Powerful model for complex tasks

          - `:"claude-sonnet-4-0"`

            High-performance model with extended thinking

          - `:"claude-sonnet-4-20250514"`

            High-performance model with extended thinking

          - `:"claude-3-haiku-20240307"`

            Fast and cost-effective model

        - `String = String`

    - `to: BetaFallbackInfo`

      The fallback model producing the content that follows this block. Its `model` is always the canonical id.

    - `type: :fallback`

      - `:fallback`

### Beta Content Block Param

- `BetaContentBlockParam = BetaTextBlockParam | BetaImageBlockParam | BetaRequestDocumentBlock | 19 more`

  Regular text content.

  - `class BetaTextBlockParam`

    - `text: String`

    - `type: :text`

      - `:text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

    - `citations: Array[BetaTextCitationParam]`

      - `class BetaCitationCharLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationWebSearchResultLocationParam`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

  - `class BetaImageBlockParam`

    - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

      - `class BetaBase64ImageSource`

        - `data: String`

        - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

          - `:"image/jpeg"`

          - `:"image/png"`

          - `:"image/gif"`

          - `:"image/webp"`

        - `type: :base64`

          - `:base64`

      - `class BetaURLImageSource`

        - `type: :url`

          - `:url`

        - `url: String`

      - `class BetaFileImageSource`

        - `file_id: String`

        - `type: :file`

          - `:file`

    - `type: :image`

      - `:image`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaRequestDocumentBlock`

    - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

      - `class BetaBase64PDFSource`

        - `data: String`

        - `media_type: :"application/pdf"`

          - `:"application/pdf"`

        - `type: :base64`

          - `:base64`

      - `class BetaPlainTextSource`

        - `data: String`

        - `media_type: :"text/plain"`

          - `:"text/plain"`

        - `type: :text`

          - `:text`

      - `class BetaContentBlockSource`

        - `content: String | Array[BetaContentBlockSourceContent]`

          - `String = String`

          - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

            - `class BetaTextBlockParam`

            - `class BetaImageBlockParam`

        - `type: :content`

          - `:content`

      - `class BetaURLPDFSource`

        - `type: :url`

          - `:url`

        - `url: String`

      - `class BetaFileDocumentSource`

        - `file_id: String`

        - `type: :file`

          - `:file`

    - `type: :document`

      - `:document`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      - `enabled: bool`

    - `context: String`

    - `title: String`

  - `class BetaSearchResultBlockParam`

    - `content: Array[BetaTextBlockParam]`

      - `text: String`

      - `type: :text`

      - `cache_control: BetaCacheControlEphemeral`

        Create a cache control breakpoint at this content block.

      - `citations: Array[BetaTextCitationParam]`

    - `source: String`

    - `title: String`

    - `type: :search_result`

      - `:search_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

  - `class BetaThinkingBlockParam`

    - `signature: String`

    - `thinking: String`

    - `type: :thinking`

      - `:thinking`

  - `class BetaRedactedThinkingBlockParam`

    - `data: String`

    - `type: :redacted_thinking`

      - `:redacted_thinking`

  - `class BetaToolUseBlockParam`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: String`

    - `type: :tool_use`

      - `:tool_use`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

        - `type: :direct`

          - `:direct`

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

        - `tool_id: String`

        - `type: :code_execution_20250825`

          - `:code_execution_20250825`

      - `class BetaServerToolCaller20260120`

        - `tool_id: String`

        - `type: :code_execution_20260120`

          - `:code_execution_20260120`

  - `class BetaToolResultBlockParam`

    - `tool_use_id: String`

    - `type: :tool_result`

      - `:tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

      - `String = String`

      - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

        - `class BetaTextBlockParam`

        - `class BetaImageBlockParam`

        - `class BetaSearchResultBlockParam`

        - `class BetaRequestDocumentBlock`

        - `class BetaToolReferenceBlockParam`

          Tool reference block that can be included in tool_result content.

          - `tool_name: String`

          - `type: :tool_reference`

            - `:tool_reference`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

    - `is_error: bool`

  - `class BetaServerToolUseBlockParam`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: :advisor | :web_search | :web_fetch | 5 more`

      - `:advisor`

      - `:web_search`

      - `:web_fetch`

      - `:code_execution`

      - `:bash_code_execution`

      - `:text_editor_code_execution`

      - `:tool_search_tool_regex`

      - `:tool_search_tool_bm25`

    - `type: :server_tool_use`

      - `:server_tool_use`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaWebSearchToolResultBlockParam`

    - `content: BetaWebSearchToolResultBlockParamContent`

      - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

        - `encrypted_content: String`

        - `title: String`

        - `type: :web_search_result`

          - `:web_search_result`

        - `url: String`

        - `page_age: String`

      - `class BetaWebSearchToolRequestError`

        - `error_code: BetaWebSearchToolResultErrorCode`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:max_uses_exceeded`

          - `:too_many_requests`

          - `:query_too_long`

          - `:request_too_large`

        - `type: :web_search_tool_result_error`

          - `:web_search_tool_result_error`

    - `tool_use_id: String`

    - `type: :web_search_tool_result`

      - `:web_search_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaWebFetchToolResultBlockParam`

    - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

      - `class BetaWebFetchToolResultErrorBlockParam`

        - `error_code: BetaWebFetchToolResultErrorCode`

          - `:invalid_tool_input`

          - `:url_too_long`

          - `:url_not_allowed`

          - `:url_not_in_prior_context`

          - `:url_not_accessible`

          - `:unsupported_content_type`

          - `:too_many_requests`

          - `:max_uses_exceeded`

          - `:unavailable`

        - `type: :web_fetch_tool_result_error`

          - `:web_fetch_tool_result_error`

      - `class BetaWebFetchBlockParam`

        - `content: BetaRequestDocumentBlock`

        - `type: :web_fetch_result`

          - `:web_fetch_result`

        - `url: String`

          Fetched content URL

        - `retrieved_at: String`

          ISO 8601 timestamp when the content was retrieved

    - `tool_use_id: String`

    - `type: :web_fetch_tool_result`

      - `:web_fetch_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

      Tool invocation directly from the model.

      - `class BetaDirectCaller`

        Tool invocation directly from the model.

      - `class BetaServerToolCaller`

        Tool invocation generated by a server-side tool.

      - `class BetaServerToolCaller20260120`

  - `class BetaAdvisorToolResultBlockParam`

    - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

      - `class BetaAdvisorToolResultErrorParam`

        - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

          - `:max_uses_exceeded`

          - `:prompt_too_long`

          - `:too_many_requests`

          - `:overloaded`

          - `:unavailable`

          - `:execution_time_exceeded`

          - `:model_not_found`

        - `type: :advisor_tool_result_error`

          - `:advisor_tool_result_error`

      - `class BetaAdvisorResultBlockParam`

        - `text: String`

        - `type: :advisor_result`

          - `:advisor_result`

        - `stop_reason: String`

      - `class BetaAdvisorRedactedResultBlockParam`

        - `encrypted_content: String`

          Opaque blob produced by a prior response; must be round-tripped verbatim.

        - `type: :advisor_redacted_result`

          - `:advisor_redacted_result`

        - `stop_reason: String`

    - `tool_use_id: String`

    - `type: :advisor_tool_result`

      - `:advisor_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaCodeExecutionToolResultBlockParam`

    - `content: BetaCodeExecutionToolResultBlockParamContent`

      Code execution result with encrypted stdout for PFC + web_search results.

      - `class BetaCodeExecutionToolResultErrorParam`

        - `error_code: BetaCodeExecutionToolResultErrorCode`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

        - `type: :code_execution_tool_result_error`

          - `:code_execution_tool_result_error`

      - `class BetaCodeExecutionResultBlockParam`

        - `content: Array[BetaCodeExecutionOutputBlockParam]`

          - `file_id: String`

          - `type: :code_execution_output`

            - `:code_execution_output`

        - `return_code: Integer`

        - `stderr: String`

        - `stdout: String`

        - `type: :code_execution_result`

          - `:code_execution_result`

      - `class BetaEncryptedCodeExecutionResultBlockParam`

        Code execution result with encrypted stdout for PFC + web_search results.

        - `content: Array[BetaCodeExecutionOutputBlockParam]`

          - `file_id: String`

          - `type: :code_execution_output`

        - `encrypted_stdout: String`

        - `return_code: Integer`

        - `stderr: String`

        - `type: :encrypted_code_execution_result`

          - `:encrypted_code_execution_result`

    - `tool_use_id: String`

    - `type: :code_execution_tool_result`

      - `:code_execution_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaBashCodeExecutionToolResultBlockParam`

    - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

      - `class BetaBashCodeExecutionToolResultErrorParam`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

          - `:output_file_too_large`

        - `type: :bash_code_execution_tool_result_error`

          - `:bash_code_execution_tool_result_error`

      - `class BetaBashCodeExecutionResultBlockParam`

        - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

          - `file_id: String`

          - `type: :bash_code_execution_output`

            - `:bash_code_execution_output`

        - `return_code: Integer`

        - `stderr: String`

        - `stdout: String`

        - `type: :bash_code_execution_result`

          - `:bash_code_execution_result`

    - `tool_use_id: String`

    - `type: :bash_code_execution_tool_result`

      - `:bash_code_execution_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaTextEditorCodeExecutionToolResultBlockParam`

    - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

      - `class BetaTextEditorCodeExecutionToolResultErrorParam`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

          - `:file_not_found`

        - `type: :text_editor_code_execution_tool_result_error`

          - `:text_editor_code_execution_tool_result_error`

        - `error_message: String`

      - `class BetaTextEditorCodeExecutionViewResultBlockParam`

        - `content: String`

        - `file_type: :text | :image | :pdf`

          - `:text`

          - `:image`

          - `:pdf`

        - `type: :text_editor_code_execution_view_result`

          - `:text_editor_code_execution_view_result`

        - `num_lines: Integer`

        - `start_line: Integer`

        - `total_lines: Integer`

      - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

        - `is_file_update: bool`

        - `type: :text_editor_code_execution_create_result`

          - `:text_editor_code_execution_create_result`

      - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

        - `type: :text_editor_code_execution_str_replace_result`

          - `:text_editor_code_execution_str_replace_result`

        - `lines: Array[String]`

        - `new_lines: Integer`

        - `new_start: Integer`

        - `old_lines: Integer`

        - `old_start: Integer`

    - `tool_use_id: String`

    - `type: :text_editor_code_execution_tool_result`

      - `:text_editor_code_execution_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaToolSearchToolResultBlockParam`

    - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

      - `class BetaToolSearchToolResultErrorParam`

        - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

          - `:invalid_tool_input`

          - `:unavailable`

          - `:too_many_requests`

          - `:execution_time_exceeded`

        - `type: :tool_search_tool_result_error`

          - `:tool_search_tool_result_error`

        - `error_message: String`

      - `class BetaToolSearchToolSearchResultBlockParam`

        - `tool_references: Array[BetaToolReferenceBlockParam]`

          - `tool_name: String`

          - `type: :tool_reference`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

        - `type: :tool_search_tool_search_result`

          - `:tool_search_tool_search_result`

    - `tool_use_id: String`

    - `type: :tool_search_tool_result`

      - `:tool_search_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaMCPToolUseBlockParam`

    - `id: String`

    - `input: Hash[Symbol, untyped]`

    - `name: String`

    - `server_name: String`

      The name of the MCP server

    - `type: :mcp_tool_use`

      - `:mcp_tool_use`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaRequestMCPToolResultBlockParam`

    - `tool_use_id: String`

    - `type: :mcp_tool_result`

      - `:mcp_tool_result`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `content: String | Array[BetaTextBlockParam]`

      - `String = String`

      - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

        - `text: String`

        - `type: :text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: Array[BetaTextCitationParam]`

    - `is_error: bool`

  - `class BetaContainerUploadBlockParam`

    A content block that represents a file to be uploaded to the container
    Files uploaded via this block will be available in the container's input directory.

    - `file_id: String`

    - `type: :container_upload`

      - `:container_upload`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaCompactionBlockParam`

    A compaction block containing summary of previous context.

    Users should round-trip these blocks from responses to subsequent requests
    to maintain context across compaction boundaries.

    When content is None, the block represents a failed compaction. The server
    treats these as no-ops. Empty string content is not allowed.

    - `type: :compaction`

      - `:compaction`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `content: String`

      Summary of previously compacted content, or null if compaction failed

    - `encrypted_content: String`

      Opaque metadata from prior compaction, to be round-tripped verbatim

  - `class BetaMidConversationSystemBlockParam`

    System instructions that appear mid-conversation.

    Use this block to provide or update system-level instructions at a specific
    point in the conversation, rather than only via the top-level `system` parameter.

    - `content: Array[BetaTextBlockParam]`

      System instruction text blocks.

      - `text: String`

      - `type: :text`

      - `cache_control: BetaCacheControlEphemeral`

        Create a cache control breakpoint at this content block.

      - `citations: Array[BetaTextCitationParam]`

    - `type: :mid_conv_system`

      - `:mid_conv_system`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

  - `class BetaFallbackBlockParam`

    A `fallback` block echoed back from a prior response.

    Accepted in `messages[].content` and never rendered into the prompt,
    not validated against the request's `fallbacks` chain or top-level
    `model`, and stripped before the sticky-routing cache key is computed.

    Callers should echo the assistant turn verbatim — block included. The
    block's position is load-bearing for thinking verification: the thinking
    runs on either side of a fallback hop carry independently-rooted
    verification hash chains, and this block is the only record of where one
    chain ends and the next begins. When thinking runs flank the boundary,
    omitting the block merges the runs into one contiguous span whose hashes
    cannot verify (the request is rejected), and moving it into the middle of
    a single run splits that run's chain and is likewise rejected; between
    non-thinking blocks the block's placement has no verification effect.

    - `from: BetaFallbackInfoParam`

      Identifies one hop of a fallback transition.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `:"claude-fable-5"`

            Next generation of intelligence for the hardest knowledge work and coding problems

          - `:"claude-mythos-5"`

            Most capable model for cybersecurity and biology research

          - `:"claude-opus-4-8"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-opus-4-7"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-mythos-preview"`

            New class of intelligence, strongest in coding and cybersecurity

          - `:"claude-opus-4-6"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-sonnet-4-6"`

            Best combination of speed and intelligence

          - `:"claude-haiku-4-5"`

            Fastest model with near-frontier intelligence

          - `:"claude-haiku-4-5-20251001"`

            Fastest model with near-frontier intelligence

          - `:"claude-opus-4-5"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-opus-4-5-20251101"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-sonnet-4-5"`

            High-performance model for agents and coding

          - `:"claude-sonnet-4-5-20250929"`

            High-performance model for agents and coding

          - `:"claude-opus-4-1"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-1-20250805"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-0"`

            Powerful model for complex tasks

          - `:"claude-opus-4-20250514"`

            Powerful model for complex tasks

          - `:"claude-sonnet-4-0"`

            High-performance model with extended thinking

          - `:"claude-sonnet-4-20250514"`

            High-performance model with extended thinking

          - `:"claude-3-haiku-20240307"`

            Fast and cost-effective model

        - `String = String`

    - `to: BetaFallbackInfoParam`

      Identifies one hop of a fallback transition.

    - `type: :fallback`

      - `:fallback`

### Beta Content Block Source

- `class BetaContentBlockSource`

  - `content: String | Array[BetaContentBlockSourceContent]`

    - `String = String`

    - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

      - `class BetaTextBlockParam`

        - `text: String`

        - `type: :text`

          - `:text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

          - `type: :ephemeral`

            - `:ephemeral`

          - `ttl: :"5m" | :"1h"`

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            - `5m`: 5 minutes
            - `1h`: 1 hour

            Defaults to `5m`.

            - `:"5m"`

            - `:"1h"`

        - `citations: Array[BetaTextCitationParam]`

          - `class BetaCitationCharLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationWebSearchResultLocationParam`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

      - `class BetaImageBlockParam`

        - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

          - `class BetaBase64ImageSource`

            - `data: String`

            - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

              - `:"image/jpeg"`

              - `:"image/png"`

              - `:"image/gif"`

              - `:"image/webp"`

            - `type: :base64`

              - `:base64`

          - `class BetaURLImageSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileImageSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :image`

          - `:image`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

  - `type: :content`

    - `:content`

### Beta Content Block Source Content

- `BetaContentBlockSourceContent = BetaTextBlockParam | BetaImageBlockParam`

  - `class BetaTextBlockParam`

    - `text: String`

    - `type: :text`

      - `:text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

    - `citations: Array[BetaTextCitationParam]`

      - `class BetaCitationCharLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationWebSearchResultLocationParam`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

  - `class BetaImageBlockParam`

    - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

      - `class BetaBase64ImageSource`

        - `data: String`

        - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

          - `:"image/jpeg"`

          - `:"image/png"`

          - `:"image/gif"`

          - `:"image/webp"`

        - `type: :base64`

          - `:base64`

      - `class BetaURLImageSource`

        - `type: :url`

          - `:url`

        - `url: String`

      - `class BetaFileImageSource`

        - `file_id: String`

        - `type: :file`

          - `:file`

    - `type: :image`

      - `:image`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

### Beta Context Management Config

- `class BetaContextManagementConfig`

  - `edits: Array[BetaClearToolUses20250919Edit | BetaClearThinking20251015Edit | BetaCompact20260112Edit]`

    List of context management edits to apply

    - `class BetaClearToolUses20250919Edit`

      - `type: :clear_tool_uses_20250919`

        - `:clear_tool_uses_20250919`

      - `clear_at_least: BetaInputTokensClearAtLeast`

        Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

        - `type: :input_tokens`

          - `:input_tokens`

        - `value: Integer`

      - `clear_tool_inputs: bool | Array[String]`

        Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

        - `UnionMember0 = bool`

        - `UnionMember1 = Array[String]`

      - `exclude_tools: Array[String]`

        Tool names whose uses are preserved from clearing

      - `keep: BetaToolUsesKeep`

        Number of tool uses to retain in the conversation

        - `type: :tool_uses`

          - `:tool_uses`

        - `value: Integer`

      - `trigger: BetaInputTokensTrigger | BetaToolUsesTrigger`

        Condition that triggers the context management strategy

        - `class BetaInputTokensTrigger`

          - `type: :input_tokens`

            - `:input_tokens`

          - `value: Integer`

        - `class BetaToolUsesTrigger`

          - `type: :tool_uses`

            - `:tool_uses`

          - `value: Integer`

    - `class BetaClearThinking20251015Edit`

      - `type: :clear_thinking_20251015`

        - `:clear_thinking_20251015`

      - `keep: BetaThinkingTurns | BetaAllThinkingTurns | :all`

        Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

        - `class BetaThinkingTurns`

          - `type: :thinking_turns`

            - `:thinking_turns`

          - `value: Integer`

        - `class BetaAllThinkingTurns`

          - `type: :all`

            - `:all`

        - `Keep = :all`

          - `:all`

    - `class BetaCompact20260112Edit`

      Automatically compact older context when reaching the configured trigger threshold.

      - `type: :compact_20260112`

        - `:compact_20260112`

      - `instructions: String`

        Additional instructions for summarization.

      - `pause_after_compaction: bool`

        Whether to pause after compaction and return the compaction block to the user.

      - `trigger: BetaInputTokensTrigger`

        When to trigger compaction. Defaults to 150000 input tokens.

### Beta Context Management Response

- `class BetaContextManagementResponse`

  - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

    List of context management edits that were applied.

    - `class BetaClearToolUses20250919EditResponse`

      - `cleared_input_tokens: Integer`

        Number of input tokens cleared by this edit.

      - `cleared_tool_uses: Integer`

        Number of tool uses that were cleared.

      - `type: :clear_tool_uses_20250919`

        The type of context management edit applied.

        - `:clear_tool_uses_20250919`

    - `class BetaClearThinking20251015EditResponse`

      - `cleared_input_tokens: Integer`

        Number of input tokens cleared by this edit.

      - `cleared_thinking_turns: Integer`

        Number of thinking turns that were cleared.

      - `type: :clear_thinking_20251015`

        The type of context management edit applied.

        - `:clear_thinking_20251015`

### Beta Count Tokens Context Management Response

- `class BetaCountTokensContextManagementResponse`

  - `original_input_tokens: Integer`

    The original token count before context management was applied

### Beta Diagnostics

- `class BetaDiagnostics`

  Response envelope for request-level diagnostics. Present (possibly
  null) whenever the caller supplied `diagnostics` on the request.

  - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

    Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

    - `class BetaCacheMissModelChanged`

      - `cache_missed_input_tokens: Integer`

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      - `type: :model_changed`

        - `:model_changed`

    - `class BetaCacheMissSystemChanged`

      - `cache_missed_input_tokens: Integer`

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      - `type: :system_changed`

        - `:system_changed`

    - `class BetaCacheMissToolsChanged`

      - `cache_missed_input_tokens: Integer`

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      - `type: :tools_changed`

        - `:tools_changed`

    - `class BetaCacheMissMessagesChanged`

      - `cache_missed_input_tokens: Integer`

        Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

      - `type: :messages_changed`

        - `:messages_changed`

    - `class BetaCacheMissPreviousMessageNotFound`

      - `type: :previous_message_not_found`

        - `:previous_message_not_found`

    - `class BetaCacheMissUnavailable`

      - `type: :unavailable`

        - `:unavailable`

### Beta Diagnostics Param

- `class BetaDiagnosticsParam`

  Request-level diagnostics. Currently carries the previous response
  id for prompt-cache divergence reporting.

  - `previous_message_id: String`

    The `id` (`msg_...`) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns `diagnostics.cache_miss_reason` when the prompt-cache prefix could not be reused. Pass `null` on the first turn to opt in without a prior message to compare.

### Beta Direct Caller

- `class BetaDirectCaller`

  Tool invocation directly from the model.

  - `type: :direct`

    - `:direct`

### Beta Document Block

- `class BetaDocumentBlock`

  - `citations: BetaCitationConfig`

    Citation configuration for the document

    - `enabled: bool`

  - `source: BetaBase64PDFSource | BetaPlainTextSource`

    - `class BetaBase64PDFSource`

      - `data: String`

      - `media_type: :"application/pdf"`

        - `:"application/pdf"`

      - `type: :base64`

        - `:base64`

    - `class BetaPlainTextSource`

      - `data: String`

      - `media_type: :"text/plain"`

        - `:"text/plain"`

      - `type: :text`

        - `:text`

  - `title: String`

    The title of the document

  - `type: :document`

    - `:document`

### Beta Encrypted Code Execution Result Block

- `class BetaEncryptedCodeExecutionResultBlock`

  Code execution result with encrypted stdout for PFC + web_search results.

  - `content: Array[BetaCodeExecutionOutputBlock]`

    - `file_id: String`

    - `type: :code_execution_output`

      - `:code_execution_output`

  - `encrypted_stdout: String`

  - `return_code: Integer`

  - `stderr: String`

  - `type: :encrypted_code_execution_result`

    - `:encrypted_code_execution_result`

### Beta Encrypted Code Execution Result Block Param

- `class BetaEncryptedCodeExecutionResultBlockParam`

  Code execution result with encrypted stdout for PFC + web_search results.

  - `content: Array[BetaCodeExecutionOutputBlockParam]`

    - `file_id: String`

    - `type: :code_execution_output`

      - `:code_execution_output`

  - `encrypted_stdout: String`

  - `return_code: Integer`

  - `stderr: String`

  - `type: :encrypted_code_execution_result`

    - `:encrypted_code_execution_result`

### Beta Fallback Block

- `class BetaFallbackBlock`

  Marks the point in `content` where one model's output gives way to the next.

  One block appears per hop where a preceding model actually ran this turn and
  declined. A turn routed directly by the sticky decision has no such boundary
  and carries no block — the signal for whether a fallback model served the
  response is the presence of a `fallback_message` entry in
  `usage.iterations`, not this block.

  The block is treated like a server-tool content block for streaming: it
  arrives via the standard `content_block_start` / `content_block_stop`
  pair and carries no deltas.

  - `from: BetaFallbackInfo`

    The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `:"claude-fable-5"`

          Next generation of intelligence for the hardest knowledge work and coding problems

        - `:"claude-mythos-5"`

          Most capable model for cybersecurity and biology research

        - `:"claude-opus-4-8"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-opus-4-7"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-mythos-preview"`

          New class of intelligence, strongest in coding and cybersecurity

        - `:"claude-opus-4-6"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-sonnet-4-6"`

          Best combination of speed and intelligence

        - `:"claude-haiku-4-5"`

          Fastest model with near-frontier intelligence

        - `:"claude-haiku-4-5-20251001"`

          Fastest model with near-frontier intelligence

        - `:"claude-opus-4-5"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-opus-4-5-20251101"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-sonnet-4-5"`

          High-performance model for agents and coding

        - `:"claude-sonnet-4-5-20250929"`

          High-performance model for agents and coding

        - `:"claude-opus-4-1"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-1-20250805"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-0"`

          Powerful model for complex tasks

        - `:"claude-opus-4-20250514"`

          Powerful model for complex tasks

        - `:"claude-sonnet-4-0"`

          High-performance model with extended thinking

        - `:"claude-sonnet-4-20250514"`

          High-performance model with extended thinking

        - `:"claude-3-haiku-20240307"`

          Fast and cost-effective model

      - `String = String`

  - `to: BetaFallbackInfo`

    The fallback model producing the content that follows this block. Its `model` is always the canonical id.

  - `type: :fallback`

    - `:fallback`

### Beta Fallback Block Param

- `class BetaFallbackBlockParam`

  A `fallback` block echoed back from a prior response.

  Accepted in `messages[].content` and never rendered into the prompt,
  not validated against the request's `fallbacks` chain or top-level
  `model`, and stripped before the sticky-routing cache key is computed.

  Callers should echo the assistant turn verbatim — block included. The
  block's position is load-bearing for thinking verification: the thinking
  runs on either side of a fallback hop carry independently-rooted
  verification hash chains, and this block is the only record of where one
  chain ends and the next begins. When thinking runs flank the boundary,
  omitting the block merges the runs into one contiguous span whose hashes
  cannot verify (the request is rejected), and moving it into the middle of
  a single run splits that run's chain and is likewise rejected; between
  non-thinking blocks the block's placement has no verification effect.

  - `from: BetaFallbackInfoParam`

    Identifies one hop of a fallback transition.

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `:"claude-fable-5"`

          Next generation of intelligence for the hardest knowledge work and coding problems

        - `:"claude-mythos-5"`

          Most capable model for cybersecurity and biology research

        - `:"claude-opus-4-8"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-opus-4-7"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-mythos-preview"`

          New class of intelligence, strongest in coding and cybersecurity

        - `:"claude-opus-4-6"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-sonnet-4-6"`

          Best combination of speed and intelligence

        - `:"claude-haiku-4-5"`

          Fastest model with near-frontier intelligence

        - `:"claude-haiku-4-5-20251001"`

          Fastest model with near-frontier intelligence

        - `:"claude-opus-4-5"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-opus-4-5-20251101"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-sonnet-4-5"`

          High-performance model for agents and coding

        - `:"claude-sonnet-4-5-20250929"`

          High-performance model for agents and coding

        - `:"claude-opus-4-1"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-1-20250805"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-0"`

          Powerful model for complex tasks

        - `:"claude-opus-4-20250514"`

          Powerful model for complex tasks

        - `:"claude-sonnet-4-0"`

          High-performance model with extended thinking

        - `:"claude-sonnet-4-20250514"`

          High-performance model with extended thinking

        - `:"claude-3-haiku-20240307"`

          Fast and cost-effective model

      - `String = String`

  - `to: BetaFallbackInfoParam`

    Identifies one hop of a fallback transition.

  - `type: :fallback`

    - `:fallback`

### Beta Fallback Info

- `class BetaFallbackInfo`

  Identifies one hop of a fallback transition.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

### Beta Fallback Info Param

- `class BetaFallbackInfoParam`

  Identifies one hop of a fallback transition.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

### Beta Fallback Message Iteration Usage

- `class BetaFallbackMessageIterationUsage`

  Token usage for the fallback-model attempt of a server-side fallback request.

  Produced in place of a `message` entry for whichever hop served the
  response. A declined hop produces the existing `message` entry. Whether
  a fallback model served the response is signalled by the presence of this
  entry in `usage.iterations`.

  - `cache_creation: BetaCacheCreation`

    Breakdown of cached tokens by TTL

    - `ephemeral_1h_input_tokens: Integer`

      The number of input tokens used to create the 1 hour cache entry.

    - `ephemeral_5m_input_tokens: Integer`

      The number of input tokens used to create the 5 minute cache entry.

  - `cache_creation_input_tokens: Integer`

    The number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The number of input tokens read from the cache.

  - `input_tokens: Integer`

    The number of input tokens which were used.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

  - `output_tokens: Integer`

    The number of output tokens which were used.

  - `type: :fallback_message`

    Usage for the fallback-model attempt that served the response

    - `:fallback_message`

### Beta Fallback Param

- `class BetaFallbackParam`

  One entry in the `fallbacks` chain on a `/v1/messages` request.

  `model` is required. The four override fields (`max_tokens`, `thinking`,
  `output_config`, and `speed`) replace the corresponding top-level field
  for this attempt only and are validated as if the request were made to
  `model`. Any other key is rejected at parse time.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

  - `max_tokens: Integer`

  - `output_config: BetaOutputConfig`

    - `effort: :low | :medium | :high | 2 more`

      All possible effort levels.

      - `:low`

      - `:medium`

      - `:high`

      - `:xhigh`

      - `:max`

    - `format_: BetaJSONOutputFormat`

      A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

      - `schema: Hash[Symbol, untyped]`

        The JSON schema of the format

      - `type: :json_schema`

        - `:json_schema`

    - `task_budget: BetaTokenTaskBudget`

      User-configurable total token budget across contexts.

      - `total: Integer`

        Total token budget across all contexts in the session.

      - `type: :tokens`

        The budget type. Currently only 'tokens' is supported.

        - `:tokens`

      - `remaining: Integer`

        Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

  - `speed: :standard | :fast`

    - `:standard`

    - `:fast`

  - `thinking: BetaThinkingConfigEnabled | BetaThinkingConfigDisabled | BetaThinkingConfigAdaptive`

    - `class BetaThinkingConfigEnabled`

      - `budget_tokens: Integer`

        Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

        Must be ≥1024 and less than `max_tokens`.

        See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

      - `type: :enabled`

        - `:enabled`

      - `display_: :summarized | :omitted`

        Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

        - `:summarized`

        - `:omitted`

    - `class BetaThinkingConfigDisabled`

      - `type: :disabled`

        - `:disabled`

    - `class BetaThinkingConfigAdaptive`

      - `type: :adaptive`

        - `:adaptive`

      - `display_: :summarized | :omitted`

        Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

        - `:summarized`

        - `:omitted`

### Beta File Document Source

- `class BetaFileDocumentSource`

  - `file_id: String`

  - `type: :file`

    - `:file`

### Beta File Image Source

- `class BetaFileImageSource`

  - `file_id: String`

  - `type: :file`

    - `:file`

### Beta Image Block Param

- `class BetaImageBlockParam`

  - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

    - `class BetaBase64ImageSource`

      - `data: String`

      - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

        - `:"image/jpeg"`

        - `:"image/png"`

        - `:"image/gif"`

        - `:"image/webp"`

      - `type: :base64`

        - `:base64`

    - `class BetaURLImageSource`

      - `type: :url`

        - `:url`

      - `url: String`

    - `class BetaFileImageSource`

      - `file_id: String`

      - `type: :file`

        - `:file`

  - `type: :image`

    - `:image`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Input JSON Delta

- `class BetaInputJSONDelta`

  - `partial_json: String`

  - `type: :input_json_delta`

    - `:input_json_delta`

### Beta Input Tokens Clear At Least

- `class BetaInputTokensClearAtLeast`

  - `type: :input_tokens`

    - `:input_tokens`

  - `value: Integer`

### Beta Input Tokens Trigger

- `class BetaInputTokensTrigger`

  - `type: :input_tokens`

    - `:input_tokens`

  - `value: Integer`

### Beta Iterations Usage

- `BetaIterationsUsage = Array[BetaMessageIterationUsage | BetaCompactionIterationUsage | BetaAdvisorMessageIterationUsage | BetaFallbackMessageIterationUsage]`

  Per-iteration token usage breakdown.

  Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

  - Determine which iterations exceeded long context thresholds (>=200k tokens)
  - Calculate the true context window size from the last iteration
  - Understand token accumulation across server-side tool use loops

  - `class BetaMessageIterationUsage`

    Token usage for a sampling iteration.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

      - `ephemeral_1h_input_tokens: Integer`

        The number of input tokens used to create the 1 hour cache entry.

      - `ephemeral_5m_input_tokens: Integer`

        The number of input tokens used to create the 5 minute cache entry.

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `:"claude-fable-5"`

          Next generation of intelligence for the hardest knowledge work and coding problems

        - `:"claude-mythos-5"`

          Most capable model for cybersecurity and biology research

        - `:"claude-opus-4-8"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-opus-4-7"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-mythos-preview"`

          New class of intelligence, strongest in coding and cybersecurity

        - `:"claude-opus-4-6"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-sonnet-4-6"`

          Best combination of speed and intelligence

        - `:"claude-haiku-4-5"`

          Fastest model with near-frontier intelligence

        - `:"claude-haiku-4-5-20251001"`

          Fastest model with near-frontier intelligence

        - `:"claude-opus-4-5"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-opus-4-5-20251101"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-sonnet-4-5"`

          High-performance model for agents and coding

        - `:"claude-sonnet-4-5-20250929"`

          High-performance model for agents and coding

        - `:"claude-opus-4-1"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-1-20250805"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-0"`

          Powerful model for complex tasks

        - `:"claude-opus-4-20250514"`

          Powerful model for complex tasks

        - `:"claude-sonnet-4-0"`

          High-performance model with extended thinking

        - `:"claude-sonnet-4-20250514"`

          High-performance model with extended thinking

        - `:"claude-3-haiku-20240307"`

          Fast and cost-effective model

      - `String = String`

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `type: :message`

      Usage for a sampling iteration

      - `:message`

  - `class BetaCompactionIterationUsage`

    Token usage for a compaction iteration.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `type: :compaction`

      Usage for a compaction iteration

      - `:compaction`

  - `class BetaAdvisorMessageIterationUsage`

    Token usage for an advisor sub-inference iteration.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `type: :advisor_message`

      Usage for an advisor sub-inference iteration

      - `:advisor_message`

  - `class BetaFallbackMessageIterationUsage`

    Token usage for the fallback-model attempt of a server-side fallback request.

    Produced in place of a `message` entry for whichever hop served the
    response. A declined hop produces the existing `message` entry. Whether
    a fallback model served the response is signalled by the presence of this
    entry in `usage.iterations`.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `type: :fallback_message`

      Usage for the fallback-model attempt that served the response

      - `:fallback_message`

### Beta JSON Output Format

- `class BetaJSONOutputFormat`

  - `schema: Hash[Symbol, untyped]`

    The JSON schema of the format

  - `type: :json_schema`

    - `:json_schema`

### Beta MCP Tool Config

- `class BetaMCPToolConfig`

  Configuration for a specific tool in an MCP toolset.

  - `defer_loading: bool`

  - `enabled: bool`

### Beta MCP Tool Default Config

- `class BetaMCPToolDefaultConfig`

  Default configuration for tools in an MCP toolset.

  - `defer_loading: bool`

  - `enabled: bool`

### Beta MCP Tool Result Block

- `class BetaMCPToolResultBlock`

  - `content: String | Array[BetaTextBlock]`

    - `String = String`

    - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

      - `citations: Array[BetaTextCitation]`

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

        - `class BetaCitationCharLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `file_id: String`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `file_id: String`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `file_id: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationsWebSearchResultLocation`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

      - `text: String`

      - `type: :text`

        - `:text`

  - `is_error: bool`

  - `tool_use_id: String`

  - `type: :mcp_tool_result`

    - `:mcp_tool_result`

### Beta MCP Tool Use Block

- `class BetaMCPToolUseBlock`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: String`

    The name of the MCP tool

  - `server_name: String`

    The name of the MCP server

  - `type: :mcp_tool_use`

    - `:mcp_tool_use`

### Beta MCP Tool Use Block Param

- `class BetaMCPToolUseBlockParam`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: String`

  - `server_name: String`

    The name of the MCP server

  - `type: :mcp_tool_use`

    - `:mcp_tool_use`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta MCP Toolset

- `class BetaMCPToolset`

  Configuration for a group of tools from an MCP server.

  Allows configuring enabled status and defer_loading for all tools
  from an MCP server, with optional per-tool overrides.

  - `mcp_server_name: String`

    Name of the MCP server to configure tools for

  - `type: :mcp_toolset`

    - `:mcp_toolset`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `configs: Hash[Symbol, BetaMCPToolConfig]`

    Configuration overrides for specific tools, keyed by tool name

    - `defer_loading: bool`

    - `enabled: bool`

  - `default_config: BetaMCPToolDefaultConfig`

    Default configuration applied to all tools from this server

    - `defer_loading: bool`

    - `enabled: bool`

### Beta Memory Tool 20250818

- `class BetaMemoryTool20250818`

  - `name: :memory`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:memory`

  - `type: :memory_20250818`

    - `:memory_20250818`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Memory Tool 20250818 Command

- `BetaMemoryTool20250818Command = BetaMemoryTool20250818ViewCommand | BetaMemoryTool20250818CreateCommand | BetaMemoryTool20250818StrReplaceCommand | 3 more`

  - `class BetaMemoryTool20250818ViewCommand`

    - `command: :view`

      Command type identifier

      - `:view`

    - `path: String`

      Path to directory or file to view

    - `view_range: Array[Integer]`

      Optional line range for viewing specific lines

  - `class BetaMemoryTool20250818CreateCommand`

    - `command: :create`

      Command type identifier

      - `:create`

    - `file_text: String`

      Content to write to the file

    - `path: String`

      Path where the file should be created

  - `class BetaMemoryTool20250818StrReplaceCommand`

    - `command: :str_replace`

      Command type identifier

      - `:str_replace`

    - `new_str: String`

      Text to replace with

    - `old_str: String`

      Text to search for and replace

    - `path: String`

      Path to the file where text should be replaced

  - `class BetaMemoryTool20250818InsertCommand`

    - `command: :insert`

      Command type identifier

      - `:insert`

    - `insert_line: Integer`

      Line number where text should be inserted

    - `insert_text: String`

      Text to insert at the specified line

    - `path: String`

      Path to the file where text should be inserted

  - `class BetaMemoryTool20250818DeleteCommand`

    - `command: :delete`

      Command type identifier

      - `:delete`

    - `path: String`

      Path to the file or directory to delete

  - `class BetaMemoryTool20250818RenameCommand`

    - `command: :rename`

      Command type identifier

      - `:rename`

    - `new_path: String`

      New path for the file or directory

    - `old_path: String`

      Current path of the file or directory

### Beta Memory Tool 20250818 Create Command

- `class BetaMemoryTool20250818CreateCommand`

  - `command: :create`

    Command type identifier

    - `:create`

  - `file_text: String`

    Content to write to the file

  - `path: String`

    Path where the file should be created

### Beta Memory Tool 20250818 Delete Command

- `class BetaMemoryTool20250818DeleteCommand`

  - `command: :delete`

    Command type identifier

    - `:delete`

  - `path: String`

    Path to the file or directory to delete

### Beta Memory Tool 20250818 Insert Command

- `class BetaMemoryTool20250818InsertCommand`

  - `command: :insert`

    Command type identifier

    - `:insert`

  - `insert_line: Integer`

    Line number where text should be inserted

  - `insert_text: String`

    Text to insert at the specified line

  - `path: String`

    Path to the file where text should be inserted

### Beta Memory Tool 20250818 Rename Command

- `class BetaMemoryTool20250818RenameCommand`

  - `command: :rename`

    Command type identifier

    - `:rename`

  - `new_path: String`

    New path for the file or directory

  - `old_path: String`

    Current path of the file or directory

### Beta Memory Tool 20250818 Str Replace Command

- `class BetaMemoryTool20250818StrReplaceCommand`

  - `command: :str_replace`

    Command type identifier

    - `:str_replace`

  - `new_str: String`

    Text to replace with

  - `old_str: String`

    Text to search for and replace

  - `path: String`

    Path to the file where text should be replaced

### Beta Memory Tool 20250818 View Command

- `class BetaMemoryTool20250818ViewCommand`

  - `command: :view`

    Command type identifier

    - `:view`

  - `path: String`

    Path to directory or file to view

  - `view_range: Array[Integer]`

    Optional line range for viewing specific lines

### Beta Message

- `class BetaMessage`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `container: BetaContainer`

    Information about the container used in the request (for the code execution tool)

    - `id: String`

      Identifier for the container used in this request

    - `expires_at: Time`

      The time at which the container will expire.

    - `skills: Array[BetaSkill]`

      Skills loaded in the container

      - `skill_id: String`

        Skill ID

      - `type: :anthropic | :custom`

        Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

        - `:anthropic`

        - `:custom`

      - `version: String`

        Skill version or 'latest' for most recent version

  - `content: Array[BetaContentBlock]`

    Content generated by the model.

    This is an array of content blocks, each of which has a `type` that determines its shape.

    Example:

    ```json
    [{"type": "text", "text": "Hi, I'm Claude."}]
    ```

    If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

    For example, if the input `messages` were:

    ```json
    [
      {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
      {"role": "assistant", "content": "The best answer is ("}
    ]
    ```

    Then the response `content` might be:

    ```json
    [{"type": "text", "text": "B)"}]
    ```

    - `class BetaTextBlock`

      - `citations: Array[BetaTextCitation]`

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

        - `class BetaCitationCharLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `file_id: String`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `file_id: String`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `file_id: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationsWebSearchResultLocation`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

      - `text: String`

      - `type: :text`

        - `:text`

    - `class BetaThinkingBlock`

      - `signature: String`

      - `thinking: String`

      - `type: :thinking`

        - `:thinking`

    - `class BetaRedactedThinkingBlock`

      - `data: String`

      - `type: :redacted_thinking`

        - `:redacted_thinking`

    - `class BetaToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

      - `type: :tool_use`

        - `:tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

          - `type: :direct`

            - `:direct`

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

          - `tool_id: String`

          - `type: :code_execution_20250825`

            - `:code_execution_20250825`

        - `class BetaServerToolCaller20260120`

          - `tool_id: String`

          - `type: :code_execution_20260120`

            - `:code_execution_20260120`

    - `class BetaServerToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: :advisor | :web_search | :web_fetch | 5 more`

        - `:advisor`

        - `:web_search`

        - `:web_fetch`

        - `:code_execution`

        - `:bash_code_execution`

        - `:text_editor_code_execution`

        - `:tool_search_tool_regex`

        - `:tool_search_tool_bm25`

      - `type: :server_tool_use`

        - `:server_tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebSearchToolResultBlock`

      - `content: BetaWebSearchToolResultBlockContent`

        - `class BetaWebSearchToolResultError`

          - `error_code: BetaWebSearchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:max_uses_exceeded`

            - `:too_many_requests`

            - `:query_too_long`

            - `:request_too_large`

          - `type: :web_search_tool_result_error`

            - `:web_search_tool_result_error`

        - `UnionMember1 = Array[BetaWebSearchResultBlock]`

          - `encrypted_content: String`

          - `page_age: String`

          - `title: String`

          - `type: :web_search_result`

            - `:web_search_result`

          - `url: String`

      - `tool_use_id: String`

      - `type: :web_search_tool_result`

        - `:web_search_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebFetchToolResultBlock`

      - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

        - `class BetaWebFetchToolResultErrorBlock`

          - `error_code: BetaWebFetchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:url_too_long`

            - `:url_not_allowed`

            - `:url_not_in_prior_context`

            - `:url_not_accessible`

            - `:unsupported_content_type`

            - `:too_many_requests`

            - `:max_uses_exceeded`

            - `:unavailable`

          - `type: :web_fetch_tool_result_error`

            - `:web_fetch_tool_result_error`

        - `class BetaWebFetchBlock`

          - `content: BetaDocumentBlock`

            - `citations: BetaCitationConfig`

              Citation configuration for the document

              - `enabled: bool`

            - `source: BetaBase64PDFSource | BetaPlainTextSource`

              - `class BetaBase64PDFSource`

                - `data: String`

                - `media_type: :"application/pdf"`

                  - `:"application/pdf"`

                - `type: :base64`

                  - `:base64`

              - `class BetaPlainTextSource`

                - `data: String`

                - `media_type: :"text/plain"`

                  - `:"text/plain"`

                - `type: :text`

                  - `:text`

            - `title: String`

              The title of the document

            - `type: :document`

              - `:document`

          - `retrieved_at: String`

            ISO 8601 timestamp when the content was retrieved

          - `type: :web_fetch_result`

            - `:web_fetch_result`

          - `url: String`

            Fetched content URL

      - `tool_use_id: String`

      - `type: :web_fetch_tool_result`

        - `:web_fetch_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaAdvisorToolResultBlock`

      - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

        - `class BetaAdvisorToolResultError`

          - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

            - `:max_uses_exceeded`

            - `:prompt_too_long`

            - `:too_many_requests`

            - `:overloaded`

            - `:unavailable`

            - `:execution_time_exceeded`

            - `:model_not_found`

          - `type: :advisor_tool_result_error`

            - `:advisor_tool_result_error`

        - `class BetaAdvisorResultBlock`

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

          - `text: String`

          - `type: :advisor_result`

            - `:advisor_result`

        - `class BetaAdvisorRedactedResultBlock`

          - `encrypted_content: String`

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

          - `type: :advisor_redacted_result`

            - `:advisor_redacted_result`

      - `tool_use_id: String`

      - `type: :advisor_tool_result`

        - `:advisor_tool_result`

    - `class BetaCodeExecutionToolResultBlock`

      - `content: BetaCodeExecutionToolResultBlockContent`

        Code execution result with encrypted stdout for PFC + web_search results.

        - `class BetaCodeExecutionToolResultError`

          - `error_code: BetaCodeExecutionToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `type: :code_execution_tool_result_error`

            - `:code_execution_tool_result_error`

        - `class BetaCodeExecutionResultBlock`

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

              - `:code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :code_execution_result`

            - `:code_execution_result`

        - `class BetaEncryptedCodeExecutionResultBlock`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

          - `encrypted_stdout: String`

          - `return_code: Integer`

          - `stderr: String`

          - `type: :encrypted_code_execution_result`

            - `:encrypted_code_execution_result`

      - `tool_use_id: String`

      - `type: :code_execution_tool_result`

        - `:code_execution_tool_result`

    - `class BetaBashCodeExecutionToolResultBlock`

      - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

        - `class BetaBashCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:output_file_too_large`

          - `type: :bash_code_execution_tool_result_error`

            - `:bash_code_execution_tool_result_error`

        - `class BetaBashCodeExecutionResultBlock`

          - `content: Array[BetaBashCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :bash_code_execution_output`

              - `:bash_code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :bash_code_execution_result`

            - `:bash_code_execution_result`

      - `tool_use_id: String`

      - `type: :bash_code_execution_tool_result`

        - `:bash_code_execution_tool_result`

    - `class BetaTextEditorCodeExecutionToolResultBlock`

      - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

        - `class BetaTextEditorCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:file_not_found`

          - `error_message: String`

          - `type: :text_editor_code_execution_tool_result_error`

            - `:text_editor_code_execution_tool_result_error`

        - `class BetaTextEditorCodeExecutionViewResultBlock`

          - `content: String`

          - `file_type: :text | :image | :pdf`

            - `:text`

            - `:image`

            - `:pdf`

          - `num_lines: Integer`

          - `start_line: Integer`

          - `total_lines: Integer`

          - `type: :text_editor_code_execution_view_result`

            - `:text_editor_code_execution_view_result`

        - `class BetaTextEditorCodeExecutionCreateResultBlock`

          - `is_file_update: bool`

          - `type: :text_editor_code_execution_create_result`

            - `:text_editor_code_execution_create_result`

        - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

          - `lines: Array[String]`

          - `new_lines: Integer`

          - `new_start: Integer`

          - `old_lines: Integer`

          - `old_start: Integer`

          - `type: :text_editor_code_execution_str_replace_result`

            - `:text_editor_code_execution_str_replace_result`

      - `tool_use_id: String`

      - `type: :text_editor_code_execution_tool_result`

        - `:text_editor_code_execution_tool_result`

    - `class BetaToolSearchToolResultBlock`

      - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

        - `class BetaToolSearchToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `error_message: String`

          - `type: :tool_search_tool_result_error`

            - `:tool_search_tool_result_error`

        - `class BetaToolSearchToolSearchResultBlock`

          - `tool_references: Array[BetaToolReferenceBlock]`

            - `tool_name: String`

            - `type: :tool_reference`

              - `:tool_reference`

          - `type: :tool_search_tool_search_result`

            - `:tool_search_tool_search_result`

      - `tool_use_id: String`

      - `type: :tool_search_tool_result`

        - `:tool_search_tool_result`

    - `class BetaMCPToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

        The name of the MCP tool

      - `server_name: String`

        The name of the MCP server

      - `type: :mcp_tool_use`

        - `:mcp_tool_use`

    - `class BetaMCPToolResultBlock`

      - `content: String | Array[BetaTextBlock]`

        - `String = String`

        - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

          - `citations: Array[BetaTextCitation]`

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

          - `text: String`

          - `type: :text`

      - `is_error: bool`

      - `tool_use_id: String`

      - `type: :mcp_tool_result`

        - `:mcp_tool_result`

    - `class BetaContainerUploadBlock`

      Response model for a file uploaded to the container.

      - `file_id: String`

      - `type: :container_upload`

        - `:container_upload`

    - `class BetaCompactionBlock`

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid
      summary (e.g., malformed output from the model). Clients may round-trip
      compaction blocks with null content; the server treats them as no-ops.

      - `content: String`

        Summary of compacted content, or null if compaction failed

      - `encrypted_content: String`

        Opaque metadata from prior compaction, to be round-tripped verbatim

      - `type: :compaction`

        - `:compaction`

    - `class BetaFallbackBlock`

      Marks the point in `content` where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and
      declined. A turn routed directly by the sticky decision has no such boundary
      and carries no block — the signal for whether a fallback model served the
      response is the presence of a `fallback_message` entry in
      `usage.iterations`, not this block.

      The block is treated like a server-tool content block for streaming: it
      arrives via the standard `content_block_start` / `content_block_stop`
      pair and carries no deltas.

      - `from: BetaFallbackInfo`

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `:"claude-fable-5"`

              Next generation of intelligence for the hardest knowledge work and coding problems

            - `:"claude-mythos-5"`

              Most capable model for cybersecurity and biology research

            - `:"claude-opus-4-8"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-opus-4-7"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-mythos-preview"`

              New class of intelligence, strongest in coding and cybersecurity

            - `:"claude-opus-4-6"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-sonnet-4-6"`

              Best combination of speed and intelligence

            - `:"claude-haiku-4-5"`

              Fastest model with near-frontier intelligence

            - `:"claude-haiku-4-5-20251001"`

              Fastest model with near-frontier intelligence

            - `:"claude-opus-4-5"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-opus-4-5-20251101"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-sonnet-4-5"`

              High-performance model for agents and coding

            - `:"claude-sonnet-4-5-20250929"`

              High-performance model for agents and coding

            - `:"claude-opus-4-1"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-1-20250805"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-0"`

              Powerful model for complex tasks

            - `:"claude-opus-4-20250514"`

              Powerful model for complex tasks

            - `:"claude-sonnet-4-0"`

              High-performance model with extended thinking

            - `:"claude-sonnet-4-20250514"`

              High-performance model with extended thinking

            - `:"claude-3-haiku-20240307"`

              Fast and cost-effective model

          - `String = String`

      - `to: BetaFallbackInfo`

        The fallback model producing the content that follows this block. Its `model` is always the canonical id.

      - `type: :fallback`

        - `:fallback`

  - `context_management: BetaContextManagementResponse`

    Context management response.

    Information about context management strategies applied during the request.

    - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

      List of context management edits that were applied.

      - `class BetaClearToolUses20250919EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_tool_uses: Integer`

          Number of tool uses that were cleared.

        - `type: :clear_tool_uses_20250919`

          The type of context management edit applied.

          - `:clear_tool_uses_20250919`

      - `class BetaClearThinking20251015EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_thinking_turns: Integer`

          Number of thinking turns that were cleared.

        - `type: :clear_thinking_20251015`

          The type of context management edit applied.

          - `:clear_thinking_20251015`

  - `diagnostics: BetaDiagnostics`

    Response envelope for request-level diagnostics. Present (possibly
    null) whenever the caller supplied `diagnostics` on the request.

    - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

      Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

      - `class BetaCacheMissModelChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :model_changed`

          - `:model_changed`

      - `class BetaCacheMissSystemChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :system_changed`

          - `:system_changed`

      - `class BetaCacheMissToolsChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :tools_changed`

          - `:tools_changed`

      - `class BetaCacheMissMessagesChanged`

        - `cache_missed_input_tokens: Integer`

          Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

        - `type: :messages_changed`

          - `:messages_changed`

      - `class BetaCacheMissPreviousMessageNotFound`

        - `type: :previous_message_not_found`

          - `:previous_message_not_found`

      - `class BetaCacheMissUnavailable`

        - `type: :unavailable`

          - `:unavailable`

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

  - `role: :assistant`

    Conversational role of the generated message.

    This will always be `"assistant"`.

    - `:assistant`

  - `stop_details: BetaRefusalStopDetails`

    Structured information about a refusal.

    - `category: :cyber | :bio | :reasoning_extraction`

      The policy category that triggered the refusal.

      `null` when the refusal doesn't map to a named category.

      - `:cyber`

      - `:bio`

      - `:reasoning_extraction`

    - `explanation: String`

      Human-readable explanation of the refusal.

      This text is not guaranteed to be stable. `null` when no explanation is available for the category.

    - `fallback_credit_token: String`

      Opaque code that refunds the cache-miss cost when retrying this refused
      request on the fallback model. Pass it as `fallback_credit_token` on the
      retry request. Expires 5 minutes after the refusal.

      The retry is sent either with the same request body (`system`, `messages`,
      `tools`, and other render-shaping fields), or with the same body plus one
      appended `assistant` message whose content is the partial text (with any
      trailing whitespace stripped from the final text block) and paired
      server-tool blocks from this refusal — which also authorizes that
      appended turn as an assistant-prefill continuation on models that otherwise
      disallow prefill. A token minted mid-server-tool-loop whose partial content
      was continuable may only be redeemed the second way — if a same-body retry
      is rejected with a 400 saying the token must be redeemed by continuing the
      partial response, retry the second way instead. Either way: same workspace,
      same platform; a mismatch is a 400. Resending a token for an already-warm
      prefix is permitted but yields no additional credit.

      `null` when the refused model isn't eligible for a fallback credit.

    - `fallback_has_prefill_claim: bool`

      Whether the accompanying `fallback_credit_token` may be redeemed with the
      appended-assistant retry form. Only set when `fallback_credit_token` is
      present.

      `true`: retry by resending the same request body plus one appended
      `assistant` message whose content is this response's `content` with any
      trailing whitespace stripped from the final text block and unpaired
      `tool_use` blocks omitted (the same appended-turn shape described on
      `fallback_credit_token`), with the token attached. `false`: retry by
      resending the original request body unchanged, with the token attached —
      the appended-assistant form is not available for this refusal (no
      continuable partial content, or the request uses `output_format` or a
      `tool_choice` that forces tool use). One exception: when the request used
      `output_format` or a forced `tool_choice` and the refusal arrived after
      server tools (including MCP connector tools) had already executed, the
      token may not be redeemable by either retry form; if the exact-body retry
      is then rejected with a 400 saying the token must be redeemed by
      continuing the partial response, discard the token and retry without it.

      Advisory: if an appended-assistant retry is rejected with a 400 despite
      `true`, fall back to resending the original request body with the token.

    - `recommended_model: String`

      The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

    - `type: :refusal`

      - `:refusal`

  - `stop_reason: BetaStopReason`

    The reason that we stopped.

    This may be one the following values:

    * `"end_turn"`: the model reached a natural stopping point
    * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
    * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
    * `"tool_use"`: the model invoked one or more tools
    * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
    * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

    In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

    - `:end_turn`

    - `:max_tokens`

    - `:stop_sequence`

    - `:tool_use`

    - `:pause_turn`

    - `:compaction`

    - `:refusal`

    - `:model_context_window_exceeded`

  - `stop_sequence: String`

    Which custom stop sequence was generated, if any.

    This value will be a non-null string if one of your custom stop sequences was generated.

  - `type: :message`

    Object type.

    For Messages, this is always `"message"`.

    - `:message`

  - `usage: BetaUsage`

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

    For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

    - `cache_creation: BetaCacheCreation`

      Breakdown of cached tokens by TTL

      - `ephemeral_1h_input_tokens: Integer`

        The number of input tokens used to create the 1 hour cache entry.

      - `ephemeral_5m_input_tokens: Integer`

        The number of input tokens used to create the 5 minute cache entry.

    - `cache_creation_input_tokens: Integer`

      The number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The number of input tokens read from the cache.

    - `inference_geo: String`

      The geographic region where inference was performed for this request.

    - `input_tokens: Integer`

      The number of input tokens which were used.

    - `iterations: BetaIterationsUsage`

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

      - Determine which iterations exceeded long context thresholds (>=200k tokens)
      - Calculate the true context window size from the last iteration
      - Understand token accumulation across server-side tool use loops

      - `class BetaMessageIterationUsage`

        Token usage for a sampling iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :message`

          Usage for a sampling iteration

          - `:message`

      - `class BetaCompactionIterationUsage`

        Token usage for a compaction iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :compaction`

          Usage for a compaction iteration

          - `:compaction`

      - `class BetaAdvisorMessageIterationUsage`

        Token usage for an advisor sub-inference iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :advisor_message`

          Usage for an advisor sub-inference iteration

          - `:advisor_message`

      - `class BetaFallbackMessageIterationUsage`

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a `message` entry for whichever hop served the
        response. A declined hop produces the existing `message` entry. Whether
        a fallback model served the response is signalled by the presence of this
        entry in `usage.iterations`.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :fallback_message`

          Usage for the fallback-model attempt that served the response

          - `:fallback_message`

    - `output_tokens: Integer`

      The number of output tokens which were used.

    - `output_tokens_details: BetaOutputTokensDetails`

      Breakdown of output tokens by category.

      `output_tokens` remains the inclusive, authoritative total used for billing.
      This object provides a read-only decomposition for observability — for example,
      how many of the billed output tokens were spent on internal reasoning that may
      have been summarized before being returned to you.

      - `thinking_tokens: Integer`

        Number of output tokens the model generated as internal reasoning, including
        the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter)
        summarized thinking text returned in the response body. Computed by
        re-tokenizing the raw reasoning text, so it may differ from the model's exact
        generation count by a small number of tokens. Always ≤ `output_tokens`;
        `output_tokens - thinking_tokens` approximates the non-reasoning output.

    - `server_tool_use: BetaServerToolUsage`

      The number of server tool requests.

      - `web_fetch_requests: Integer`

        The number of web fetch tool requests.

      - `web_search_requests: Integer`

        The number of web search tool requests.

    - `service_tier: :standard | :priority | :batch`

      If the request used the priority, standard, or batch tier.

      - `:standard`

      - `:priority`

      - `:batch`

    - `speed: :standard | :fast`

      The inference speed mode used for this request.

      - `:standard`

      - `:fast`

### Beta Message Delta Usage

- `class BetaMessageDeltaUsage`

  - `cache_creation_input_tokens: Integer`

    The cumulative number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The cumulative number of input tokens read from the cache.

  - `input_tokens: Integer`

    The cumulative number of input tokens which were used.

  - `iterations: BetaIterationsUsage`

    Per-iteration token usage breakdown.

    Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

    - Determine which iterations exceeded long context thresholds (>=200k tokens)
    - Calculate the true context window size from the last iteration
    - Understand token accumulation across server-side tool use loops

    - `class BetaMessageIterationUsage`

      Token usage for a sampling iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

        - `ephemeral_1h_input_tokens: Integer`

          The number of input tokens used to create the 1 hour cache entry.

        - `ephemeral_5m_input_tokens: Integer`

          The number of input tokens used to create the 5 minute cache entry.

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `:"claude-fable-5"`

            Next generation of intelligence for the hardest knowledge work and coding problems

          - `:"claude-mythos-5"`

            Most capable model for cybersecurity and biology research

          - `:"claude-opus-4-8"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-opus-4-7"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-mythos-preview"`

            New class of intelligence, strongest in coding and cybersecurity

          - `:"claude-opus-4-6"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-sonnet-4-6"`

            Best combination of speed and intelligence

          - `:"claude-haiku-4-5"`

            Fastest model with near-frontier intelligence

          - `:"claude-haiku-4-5-20251001"`

            Fastest model with near-frontier intelligence

          - `:"claude-opus-4-5"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-opus-4-5-20251101"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-sonnet-4-5"`

            High-performance model for agents and coding

          - `:"claude-sonnet-4-5-20250929"`

            High-performance model for agents and coding

          - `:"claude-opus-4-1"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-1-20250805"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-0"`

            Powerful model for complex tasks

          - `:"claude-opus-4-20250514"`

            Powerful model for complex tasks

          - `:"claude-sonnet-4-0"`

            High-performance model with extended thinking

          - `:"claude-sonnet-4-20250514"`

            High-performance model with extended thinking

          - `:"claude-3-haiku-20240307"`

            Fast and cost-effective model

        - `String = String`

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :message`

        Usage for a sampling iteration

        - `:message`

    - `class BetaCompactionIterationUsage`

      Token usage for a compaction iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :compaction`

        Usage for a compaction iteration

        - `:compaction`

    - `class BetaAdvisorMessageIterationUsage`

      Token usage for an advisor sub-inference iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :advisor_message`

        Usage for an advisor sub-inference iteration

        - `:advisor_message`

    - `class BetaFallbackMessageIterationUsage`

      Token usage for the fallback-model attempt of a server-side fallback request.

      Produced in place of a `message` entry for whichever hop served the
      response. A declined hop produces the existing `message` entry. Whether
      a fallback model served the response is signalled by the presence of this
      entry in `usage.iterations`.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :fallback_message`

        Usage for the fallback-model attempt that served the response

        - `:fallback_message`

  - `output_tokens: Integer`

    The cumulative number of output tokens which were used.

  - `output_tokens_details: BetaOutputTokensDetails`

    Breakdown of output tokens by category.

    `output_tokens` remains the inclusive, authoritative total used for billing.
    This object provides a read-only decomposition for observability — for example,
    how many of the billed output tokens were spent on internal reasoning that may
    have been summarized before being returned to you.

    - `thinking_tokens: Integer`

      Number of output tokens the model generated as internal reasoning, including
      the thinking-block delimiter tokens.

      Reflects the raw reasoning the model produced, not the (possibly shorter)
      summarized thinking text returned in the response body. Computed by
      re-tokenizing the raw reasoning text, so it may differ from the model's exact
      generation count by a small number of tokens. Always ≤ `output_tokens`;
      `output_tokens - thinking_tokens` approximates the non-reasoning output.

  - `server_tool_use: BetaServerToolUsage`

    The number of server tool requests.

    - `web_fetch_requests: Integer`

      The number of web fetch tool requests.

    - `web_search_requests: Integer`

      The number of web search tool requests.

### Beta Message Iteration Usage

- `class BetaMessageIterationUsage`

  Token usage for a sampling iteration.

  - `cache_creation: BetaCacheCreation`

    Breakdown of cached tokens by TTL

    - `ephemeral_1h_input_tokens: Integer`

      The number of input tokens used to create the 1 hour cache entry.

    - `ephemeral_5m_input_tokens: Integer`

      The number of input tokens used to create the 5 minute cache entry.

  - `cache_creation_input_tokens: Integer`

    The number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The number of input tokens read from the cache.

  - `input_tokens: Integer`

    The number of input tokens which were used.

  - `model: Model`

    The model that will complete your prompt.

    See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `:"claude-fable-5"`

        Next generation of intelligence for the hardest knowledge work and coding problems

      - `:"claude-mythos-5"`

        Most capable model for cybersecurity and biology research

      - `:"claude-opus-4-8"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-opus-4-7"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-mythos-preview"`

        New class of intelligence, strongest in coding and cybersecurity

      - `:"claude-opus-4-6"`

        Frontier intelligence for long-running agents and coding

      - `:"claude-sonnet-4-6"`

        Best combination of speed and intelligence

      - `:"claude-haiku-4-5"`

        Fastest model with near-frontier intelligence

      - `:"claude-haiku-4-5-20251001"`

        Fastest model with near-frontier intelligence

      - `:"claude-opus-4-5"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-opus-4-5-20251101"`

        Premium model combining maximum intelligence with practical performance

      - `:"claude-sonnet-4-5"`

        High-performance model for agents and coding

      - `:"claude-sonnet-4-5-20250929"`

        High-performance model for agents and coding

      - `:"claude-opus-4-1"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-1-20250805"`

        Exceptional model for specialized complex tasks

      - `:"claude-opus-4-0"`

        Powerful model for complex tasks

      - `:"claude-opus-4-20250514"`

        Powerful model for complex tasks

      - `:"claude-sonnet-4-0"`

        High-performance model with extended thinking

      - `:"claude-sonnet-4-20250514"`

        High-performance model with extended thinking

      - `:"claude-3-haiku-20240307"`

        Fast and cost-effective model

    - `String = String`

  - `output_tokens: Integer`

    The number of output tokens which were used.

  - `type: :message`

    Usage for a sampling iteration

    - `:message`

### Beta Message Param

- `class BetaMessageParam`

  - `content: String | Array[BetaContentBlockParam]`

    - `String = String`

    - `UnionMember1 = Array[BetaContentBlockParam]`

      - `class BetaTextBlockParam`

        - `text: String`

        - `type: :text`

          - `:text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

          - `type: :ephemeral`

            - `:ephemeral`

          - `ttl: :"5m" | :"1h"`

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            - `5m`: 5 minutes
            - `1h`: 1 hour

            Defaults to `5m`.

            - `:"5m"`

            - `:"1h"`

        - `citations: Array[BetaTextCitationParam]`

          - `class BetaCitationCharLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationWebSearchResultLocationParam`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

      - `class BetaImageBlockParam`

        - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

          - `class BetaBase64ImageSource`

            - `data: String`

            - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

              - `:"image/jpeg"`

              - `:"image/png"`

              - `:"image/gif"`

              - `:"image/webp"`

            - `type: :base64`

              - `:base64`

          - `class BetaURLImageSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileImageSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :image`

          - `:image`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestDocumentBlock`

        - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

          - `class BetaContentBlockSource`

            - `content: String | Array[BetaContentBlockSourceContent]`

              - `String = String`

              - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                - `class BetaTextBlockParam`

                - `class BetaImageBlockParam`

            - `type: :content`

              - `:content`

          - `class BetaURLPDFSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileDocumentSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :document`

          - `:document`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          - `enabled: bool`

        - `context: String`

        - `title: String`

      - `class BetaSearchResultBlockParam`

        - `content: Array[BetaTextBlockParam]`

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `source: String`

        - `title: String`

        - `type: :search_result`

          - `:search_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

      - `class BetaThinkingBlockParam`

        - `signature: String`

        - `thinking: String`

        - `type: :thinking`

          - `:thinking`

      - `class BetaRedactedThinkingBlockParam`

        - `data: String`

        - `type: :redacted_thinking`

          - `:redacted_thinking`

      - `class BetaToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `type: :tool_use`

          - `:tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

            - `type: :direct`

              - `:direct`

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

            - `tool_id: String`

            - `type: :code_execution_20250825`

              - `:code_execution_20250825`

          - `class BetaServerToolCaller20260120`

            - `tool_id: String`

            - `type: :code_execution_20260120`

              - `:code_execution_20260120`

      - `class BetaToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :tool_result`

          - `:tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

          - `String = String`

          - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

            - `class BetaTextBlockParam`

            - `class BetaImageBlockParam`

            - `class BetaSearchResultBlockParam`

            - `class BetaRequestDocumentBlock`

            - `class BetaToolReferenceBlockParam`

              Tool reference block that can be included in tool_result content.

              - `tool_name: String`

              - `type: :tool_reference`

                - `:tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

        - `is_error: bool`

      - `class BetaServerToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: :advisor | :web_search | :web_fetch | 5 more`

          - `:advisor`

          - `:web_search`

          - `:web_fetch`

          - `:code_execution`

          - `:bash_code_execution`

          - `:text_editor_code_execution`

          - `:tool_search_tool_regex`

          - `:tool_search_tool_bm25`

        - `type: :server_tool_use`

          - `:server_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebSearchToolResultBlockParam`

        - `content: BetaWebSearchToolResultBlockParamContent`

          - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

            - `encrypted_content: String`

            - `title: String`

            - `type: :web_search_result`

              - `:web_search_result`

            - `url: String`

            - `page_age: String`

          - `class BetaWebSearchToolRequestError`

            - `error_code: BetaWebSearchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:max_uses_exceeded`

              - `:too_many_requests`

              - `:query_too_long`

              - `:request_too_large`

            - `type: :web_search_tool_result_error`

              - `:web_search_tool_result_error`

        - `tool_use_id: String`

        - `type: :web_search_tool_result`

          - `:web_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebFetchToolResultBlockParam`

        - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

          - `class BetaWebFetchToolResultErrorBlockParam`

            - `error_code: BetaWebFetchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:url_too_long`

              - `:url_not_allowed`

              - `:url_not_in_prior_context`

              - `:url_not_accessible`

              - `:unsupported_content_type`

              - `:too_many_requests`

              - `:max_uses_exceeded`

              - `:unavailable`

            - `type: :web_fetch_tool_result_error`

              - `:web_fetch_tool_result_error`

          - `class BetaWebFetchBlockParam`

            - `content: BetaRequestDocumentBlock`

            - `type: :web_fetch_result`

              - `:web_fetch_result`

            - `url: String`

              Fetched content URL

            - `retrieved_at: String`

              ISO 8601 timestamp when the content was retrieved

        - `tool_use_id: String`

        - `type: :web_fetch_tool_result`

          - `:web_fetch_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaAdvisorToolResultBlockParam`

        - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

          - `class BetaAdvisorToolResultErrorParam`

            - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

              - `:max_uses_exceeded`

              - `:prompt_too_long`

              - `:too_many_requests`

              - `:overloaded`

              - `:unavailable`

              - `:execution_time_exceeded`

              - `:model_not_found`

            - `type: :advisor_tool_result_error`

              - `:advisor_tool_result_error`

          - `class BetaAdvisorResultBlockParam`

            - `text: String`

            - `type: :advisor_result`

              - `:advisor_result`

            - `stop_reason: String`

          - `class BetaAdvisorRedactedResultBlockParam`

            - `encrypted_content: String`

              Opaque blob produced by a prior response; must be round-tripped verbatim.

            - `type: :advisor_redacted_result`

              - `:advisor_redacted_result`

            - `stop_reason: String`

        - `tool_use_id: String`

        - `type: :advisor_tool_result`

          - `:advisor_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCodeExecutionToolResultBlockParam`

        - `content: BetaCodeExecutionToolResultBlockParamContent`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `class BetaCodeExecutionToolResultErrorParam`

            - `error_code: BetaCodeExecutionToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :code_execution_tool_result_error`

              - `:code_execution_tool_result_error`

          - `class BetaCodeExecutionResultBlockParam`

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

                - `:code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :code_execution_result`

              - `:code_execution_result`

          - `class BetaEncryptedCodeExecutionResultBlockParam`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `content: Array[BetaCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :code_execution_output`

            - `encrypted_stdout: String`

            - `return_code: Integer`

            - `stderr: String`

            - `type: :encrypted_code_execution_result`

              - `:encrypted_code_execution_result`

        - `tool_use_id: String`

        - `type: :code_execution_tool_result`

          - `:code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaBashCodeExecutionToolResultBlockParam`

        - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

          - `class BetaBashCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:output_file_too_large`

            - `type: :bash_code_execution_tool_result_error`

              - `:bash_code_execution_tool_result_error`

          - `class BetaBashCodeExecutionResultBlockParam`

            - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

              - `file_id: String`

              - `type: :bash_code_execution_output`

                - `:bash_code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :bash_code_execution_result`

              - `:bash_code_execution_result`

        - `tool_use_id: String`

        - `type: :bash_code_execution_tool_result`

          - `:bash_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaTextEditorCodeExecutionToolResultBlockParam`

        - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

          - `class BetaTextEditorCodeExecutionToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:file_not_found`

            - `type: :text_editor_code_execution_tool_result_error`

              - `:text_editor_code_execution_tool_result_error`

            - `error_message: String`

          - `class BetaTextEditorCodeExecutionViewResultBlockParam`

            - `content: String`

            - `file_type: :text | :image | :pdf`

              - `:text`

              - `:image`

              - `:pdf`

            - `type: :text_editor_code_execution_view_result`

              - `:text_editor_code_execution_view_result`

            - `num_lines: Integer`

            - `start_line: Integer`

            - `total_lines: Integer`

          - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

            - `is_file_update: bool`

            - `type: :text_editor_code_execution_create_result`

              - `:text_editor_code_execution_create_result`

          - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

            - `type: :text_editor_code_execution_str_replace_result`

              - `:text_editor_code_execution_str_replace_result`

            - `lines: Array[String]`

            - `new_lines: Integer`

            - `new_start: Integer`

            - `old_lines: Integer`

            - `old_start: Integer`

        - `tool_use_id: String`

        - `type: :text_editor_code_execution_tool_result`

          - `:text_editor_code_execution_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaToolSearchToolResultBlockParam`

        - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

          - `class BetaToolSearchToolResultErrorParam`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :tool_search_tool_result_error`

              - `:tool_search_tool_result_error`

            - `error_message: String`

          - `class BetaToolSearchToolSearchResultBlockParam`

            - `tool_references: Array[BetaToolReferenceBlockParam]`

              - `tool_name: String`

              - `type: :tool_reference`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

            - `type: :tool_search_tool_search_result`

              - `:tool_search_tool_search_result`

        - `tool_use_id: String`

        - `type: :tool_search_tool_result`

          - `:tool_search_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaMCPToolUseBlockParam`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `server_name: String`

          The name of the MCP server

        - `type: :mcp_tool_use`

          - `:mcp_tool_use`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaRequestMCPToolResultBlockParam`

        - `tool_use_id: String`

        - `type: :mcp_tool_result`

          - `:mcp_tool_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String | Array[BetaTextBlockParam]`

          - `String = String`

          - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

            - `text: String`

            - `type: :text`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `citations: Array[BetaTextCitationParam]`

        - `is_error: bool`

      - `class BetaContainerUploadBlockParam`

        A content block that represents a file to be uploaded to the container
        Files uploaded via this block will be available in the container's input directory.

        - `file_id: String`

        - `type: :container_upload`

          - `:container_upload`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaCompactionBlockParam`

        A compaction block containing summary of previous context.

        Users should round-trip these blocks from responses to subsequent requests
        to maintain context across compaction boundaries.

        When content is None, the block represents a failed compaction. The server
        treats these as no-ops. Empty string content is not allowed.

        - `type: :compaction`

          - `:compaction`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `content: String`

          Summary of previously compacted content, or null if compaction failed

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

      - `class BetaMidConversationSystemBlockParam`

        System instructions that appear mid-conversation.

        Use this block to provide or update system-level instructions at a specific
        point in the conversation, rather than only via the top-level `system` parameter.

        - `content: Array[BetaTextBlockParam]`

          System instruction text blocks.

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `type: :mid_conv_system`

          - `:mid_conv_system`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaFallbackBlockParam`

        A `fallback` block echoed back from a prior response.

        Accepted in `messages[].content` and never rendered into the prompt,
        not validated against the request's `fallbacks` chain or top-level
        `model`, and stripped before the sticky-routing cache key is computed.

        Callers should echo the assistant turn verbatim — block included. The
        block's position is load-bearing for thinking verification: the thinking
        runs on either side of a fallback hop carry independently-rooted
        verification hash chains, and this block is the only record of where one
        chain ends and the next begins. When thinking runs flank the boundary,
        omitting the block merges the runs into one contiguous span whose hashes
        cannot verify (the request is rejected), and moving it into the middle of
        a single run splits that run's chain and is likewise rejected; between
        non-thinking blocks the block's placement has no verification effect.

        - `from: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `:"claude-fable-5"`

                Next generation of intelligence for the hardest knowledge work and coding problems

              - `:"claude-mythos-5"`

                Most capable model for cybersecurity and biology research

              - `:"claude-opus-4-8"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-opus-4-7"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-mythos-preview"`

                New class of intelligence, strongest in coding and cybersecurity

              - `:"claude-opus-4-6"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-sonnet-4-6"`

                Best combination of speed and intelligence

              - `:"claude-haiku-4-5"`

                Fastest model with near-frontier intelligence

              - `:"claude-haiku-4-5-20251001"`

                Fastest model with near-frontier intelligence

              - `:"claude-opus-4-5"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-opus-4-5-20251101"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-sonnet-4-5"`

                High-performance model for agents and coding

              - `:"claude-sonnet-4-5-20250929"`

                High-performance model for agents and coding

              - `:"claude-opus-4-1"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-1-20250805"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-0"`

                Powerful model for complex tasks

              - `:"claude-opus-4-20250514"`

                Powerful model for complex tasks

              - `:"claude-sonnet-4-0"`

                High-performance model with extended thinking

              - `:"claude-sonnet-4-20250514"`

                High-performance model with extended thinking

              - `:"claude-3-haiku-20240307"`

                Fast and cost-effective model

            - `String = String`

        - `to: BetaFallbackInfoParam`

          Identifies one hop of a fallback transition.

        - `type: :fallback`

          - `:fallback`

  - `role: :user | :assistant | :system`

    - `:user`

    - `:assistant`

    - `:system`

### Beta Message Tokens Count

- `class BetaMessageTokensCount`

  - `context_management: BetaCountTokensContextManagementResponse`

    Information about context management applied to the message.

    - `original_input_tokens: Integer`

      The original token count before context management was applied

  - `input_tokens: Integer`

    The total number of tokens across the provided list of messages, system prompt, and tools.

### Beta Metadata

- `class BetaMetadata`

  - `user_id: String`

    An external identifier for the user who is associated with the request.

    This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

### Beta Mid Conversation System Block Param

- `class BetaMidConversationSystemBlockParam`

  System instructions that appear mid-conversation.

  Use this block to provide or update system-level instructions at a specific
  point in the conversation, rather than only via the top-level `system` parameter.

  - `content: Array[BetaTextBlockParam]`

    System instruction text blocks.

    - `text: String`

    - `type: :text`

      - `:text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

    - `citations: Array[BetaTextCitationParam]`

      - `class BetaCitationCharLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationWebSearchResultLocationParam`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

  - `type: :mid_conv_system`

    - `:mid_conv_system`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

### Beta Output Config

- `class BetaOutputConfig`

  - `effort: :low | :medium | :high | 2 more`

    All possible effort levels.

    - `:low`

    - `:medium`

    - `:high`

    - `:xhigh`

    - `:max`

  - `format_: BetaJSONOutputFormat`

    A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

    - `schema: Hash[Symbol, untyped]`

      The JSON schema of the format

    - `type: :json_schema`

      - `:json_schema`

  - `task_budget: BetaTokenTaskBudget`

    User-configurable total token budget across contexts.

    - `total: Integer`

      Total token budget across all contexts in the session.

    - `type: :tokens`

      The budget type. Currently only 'tokens' is supported.

      - `:tokens`

    - `remaining: Integer`

      Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

### Beta Output Tokens Details

- `class BetaOutputTokensDetails`

  - `thinking_tokens: Integer`

    Number of output tokens the model generated as internal reasoning, including
    the thinking-block delimiter tokens.

    Reflects the raw reasoning the model produced, not the (possibly shorter)
    summarized thinking text returned in the response body. Computed by
    re-tokenizing the raw reasoning text, so it may differ from the model's exact
    generation count by a small number of tokens. Always ≤ `output_tokens`;
    `output_tokens - thinking_tokens` approximates the non-reasoning output.

### Beta Plain Text Source

- `class BetaPlainTextSource`

  - `data: String`

  - `media_type: :"text/plain"`

    - `:"text/plain"`

  - `type: :text`

    - `:text`

### Beta Raw Content Block Delta

- `BetaRawContentBlockDelta = BetaTextDelta | BetaInputJSONDelta | BetaCitationsDelta | 3 more`

  - `class BetaTextDelta`

    - `text: String`

    - `type: :text_delta`

      - `:text_delta`

  - `class BetaInputJSONDelta`

    - `partial_json: String`

    - `type: :input_json_delta`

      - `:input_json_delta`

  - `class BetaCitationsDelta`

    - `citation: BetaCitationCharLocation | BetaCitationPageLocation | BetaCitationContentBlockLocation | 2 more`

      - `class BetaCitationCharLocation`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `file_id: String`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocation`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `file_id: String`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocation`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `file_id: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationsWebSearchResultLocation`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocation`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

    - `type: :citations_delta`

      - `:citations_delta`

  - `class BetaThinkingDelta`

    - `estimated_tokens: Integer`

      Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the `thinking-token-count-2026-05-13` beta is set; `null` unless `thinking.display` resolves to `"omitted"` and a count is due this frame. Sum the increments across `thinking_delta` frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; `usage.output_tokens` remains authoritative.

    - `thinking: String`

    - `type: :thinking_delta`

      - `:thinking_delta`

  - `class BetaSignatureDelta`

    - `signature: String`

    - `type: :signature_delta`

      - `:signature_delta`

  - `class BetaCompactionContentBlockDelta`

    - `content: String`

    - `encrypted_content: String`

      Opaque metadata from prior compaction, to be round-tripped verbatim

    - `type: :compaction_delta`

      - `:compaction_delta`

### Beta Raw Content Block Delta Event

- `class BetaRawContentBlockDeltaEvent`

  - `delta: BetaRawContentBlockDelta`

    - `class BetaTextDelta`

      - `text: String`

      - `type: :text_delta`

        - `:text_delta`

    - `class BetaInputJSONDelta`

      - `partial_json: String`

      - `type: :input_json_delta`

        - `:input_json_delta`

    - `class BetaCitationsDelta`

      - `citation: BetaCitationCharLocation | BetaCitationPageLocation | BetaCitationContentBlockLocation | 2 more`

        - `class BetaCitationCharLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `file_id: String`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `file_id: String`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `file_id: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationsWebSearchResultLocation`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

      - `type: :citations_delta`

        - `:citations_delta`

    - `class BetaThinkingDelta`

      - `estimated_tokens: Integer`

        Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the `thinking-token-count-2026-05-13` beta is set; `null` unless `thinking.display` resolves to `"omitted"` and a count is due this frame. Sum the increments across `thinking_delta` frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; `usage.output_tokens` remains authoritative.

      - `thinking: String`

      - `type: :thinking_delta`

        - `:thinking_delta`

    - `class BetaSignatureDelta`

      - `signature: String`

      - `type: :signature_delta`

        - `:signature_delta`

    - `class BetaCompactionContentBlockDelta`

      - `content: String`

      - `encrypted_content: String`

        Opaque metadata from prior compaction, to be round-tripped verbatim

      - `type: :compaction_delta`

        - `:compaction_delta`

  - `index: Integer`

  - `type: :content_block_delta`

    - `:content_block_delta`

### Beta Raw Content Block Start Event

- `class BetaRawContentBlockStartEvent`

  - `content_block: BetaTextBlock | BetaThinkingBlock | BetaRedactedThinkingBlock | 14 more`

    Response model for a file uploaded to the container.

    - `class BetaTextBlock`

      - `citations: Array[BetaTextCitation]`

        Citations supporting the text block.

        The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

        - `class BetaCitationCharLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `file_id: String`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocation`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `file_id: String`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `file_id: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationsWebSearchResultLocation`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocation`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

      - `text: String`

      - `type: :text`

        - `:text`

    - `class BetaThinkingBlock`

      - `signature: String`

      - `thinking: String`

      - `type: :thinking`

        - `:thinking`

    - `class BetaRedactedThinkingBlock`

      - `data: String`

      - `type: :redacted_thinking`

        - `:redacted_thinking`

    - `class BetaToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

      - `type: :tool_use`

        - `:tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

          - `type: :direct`

            - `:direct`

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

          - `tool_id: String`

          - `type: :code_execution_20250825`

            - `:code_execution_20250825`

        - `class BetaServerToolCaller20260120`

          - `tool_id: String`

          - `type: :code_execution_20260120`

            - `:code_execution_20260120`

    - `class BetaServerToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: :advisor | :web_search | :web_fetch | 5 more`

        - `:advisor`

        - `:web_search`

        - `:web_fetch`

        - `:code_execution`

        - `:bash_code_execution`

        - `:text_editor_code_execution`

        - `:tool_search_tool_regex`

        - `:tool_search_tool_bm25`

      - `type: :server_tool_use`

        - `:server_tool_use`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebSearchToolResultBlock`

      - `content: BetaWebSearchToolResultBlockContent`

        - `class BetaWebSearchToolResultError`

          - `error_code: BetaWebSearchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:max_uses_exceeded`

            - `:too_many_requests`

            - `:query_too_long`

            - `:request_too_large`

          - `type: :web_search_tool_result_error`

            - `:web_search_tool_result_error`

        - `UnionMember1 = Array[BetaWebSearchResultBlock]`

          - `encrypted_content: String`

          - `page_age: String`

          - `title: String`

          - `type: :web_search_result`

            - `:web_search_result`

          - `url: String`

      - `tool_use_id: String`

      - `type: :web_search_tool_result`

        - `:web_search_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaWebFetchToolResultBlock`

      - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

        - `class BetaWebFetchToolResultErrorBlock`

          - `error_code: BetaWebFetchToolResultErrorCode`

            - `:invalid_tool_input`

            - `:url_too_long`

            - `:url_not_allowed`

            - `:url_not_in_prior_context`

            - `:url_not_accessible`

            - `:unsupported_content_type`

            - `:too_many_requests`

            - `:max_uses_exceeded`

            - `:unavailable`

          - `type: :web_fetch_tool_result_error`

            - `:web_fetch_tool_result_error`

        - `class BetaWebFetchBlock`

          - `content: BetaDocumentBlock`

            - `citations: BetaCitationConfig`

              Citation configuration for the document

              - `enabled: bool`

            - `source: BetaBase64PDFSource | BetaPlainTextSource`

              - `class BetaBase64PDFSource`

                - `data: String`

                - `media_type: :"application/pdf"`

                  - `:"application/pdf"`

                - `type: :base64`

                  - `:base64`

              - `class BetaPlainTextSource`

                - `data: String`

                - `media_type: :"text/plain"`

                  - `:"text/plain"`

                - `type: :text`

                  - `:text`

            - `title: String`

              The title of the document

            - `type: :document`

              - `:document`

          - `retrieved_at: String`

            ISO 8601 timestamp when the content was retrieved

          - `type: :web_fetch_result`

            - `:web_fetch_result`

          - `url: String`

            Fetched content URL

      - `tool_use_id: String`

      - `type: :web_fetch_tool_result`

        - `:web_fetch_tool_result`

      - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

        Tool invocation directly from the model.

        - `class BetaDirectCaller`

          Tool invocation directly from the model.

        - `class BetaServerToolCaller`

          Tool invocation generated by a server-side tool.

        - `class BetaServerToolCaller20260120`

    - `class BetaAdvisorToolResultBlock`

      - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

        - `class BetaAdvisorToolResultError`

          - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

            - `:max_uses_exceeded`

            - `:prompt_too_long`

            - `:too_many_requests`

            - `:overloaded`

            - `:unavailable`

            - `:execution_time_exceeded`

            - `:model_not_found`

          - `type: :advisor_tool_result_error`

            - `:advisor_tool_result_error`

        - `class BetaAdvisorResultBlock`

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

          - `text: String`

          - `type: :advisor_result`

            - `:advisor_result`

        - `class BetaAdvisorRedactedResultBlock`

          - `encrypted_content: String`

            Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

          - `stop_reason: String`

            The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

          - `type: :advisor_redacted_result`

            - `:advisor_redacted_result`

      - `tool_use_id: String`

      - `type: :advisor_tool_result`

        - `:advisor_tool_result`

    - `class BetaCodeExecutionToolResultBlock`

      - `content: BetaCodeExecutionToolResultBlockContent`

        Code execution result with encrypted stdout for PFC + web_search results.

        - `class BetaCodeExecutionToolResultError`

          - `error_code: BetaCodeExecutionToolResultErrorCode`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `type: :code_execution_tool_result_error`

            - `:code_execution_tool_result_error`

        - `class BetaCodeExecutionResultBlock`

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

              - `:code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :code_execution_result`

            - `:code_execution_result`

        - `class BetaEncryptedCodeExecutionResultBlock`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `content: Array[BetaCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :code_execution_output`

          - `encrypted_stdout: String`

          - `return_code: Integer`

          - `stderr: String`

          - `type: :encrypted_code_execution_result`

            - `:encrypted_code_execution_result`

      - `tool_use_id: String`

      - `type: :code_execution_tool_result`

        - `:code_execution_tool_result`

    - `class BetaBashCodeExecutionToolResultBlock`

      - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

        - `class BetaBashCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:output_file_too_large`

          - `type: :bash_code_execution_tool_result_error`

            - `:bash_code_execution_tool_result_error`

        - `class BetaBashCodeExecutionResultBlock`

          - `content: Array[BetaBashCodeExecutionOutputBlock]`

            - `file_id: String`

            - `type: :bash_code_execution_output`

              - `:bash_code_execution_output`

          - `return_code: Integer`

          - `stderr: String`

          - `stdout: String`

          - `type: :bash_code_execution_result`

            - `:bash_code_execution_result`

      - `tool_use_id: String`

      - `type: :bash_code_execution_tool_result`

        - `:bash_code_execution_tool_result`

    - `class BetaTextEditorCodeExecutionToolResultBlock`

      - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

        - `class BetaTextEditorCodeExecutionToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

            - `:file_not_found`

          - `error_message: String`

          - `type: :text_editor_code_execution_tool_result_error`

            - `:text_editor_code_execution_tool_result_error`

        - `class BetaTextEditorCodeExecutionViewResultBlock`

          - `content: String`

          - `file_type: :text | :image | :pdf`

            - `:text`

            - `:image`

            - `:pdf`

          - `num_lines: Integer`

          - `start_line: Integer`

          - `total_lines: Integer`

          - `type: :text_editor_code_execution_view_result`

            - `:text_editor_code_execution_view_result`

        - `class BetaTextEditorCodeExecutionCreateResultBlock`

          - `is_file_update: bool`

          - `type: :text_editor_code_execution_create_result`

            - `:text_editor_code_execution_create_result`

        - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

          - `lines: Array[String]`

          - `new_lines: Integer`

          - `new_start: Integer`

          - `old_lines: Integer`

          - `old_start: Integer`

          - `type: :text_editor_code_execution_str_replace_result`

            - `:text_editor_code_execution_str_replace_result`

      - `tool_use_id: String`

      - `type: :text_editor_code_execution_tool_result`

        - `:text_editor_code_execution_tool_result`

    - `class BetaToolSearchToolResultBlock`

      - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

        - `class BetaToolSearchToolResultError`

          - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

            - `:invalid_tool_input`

            - `:unavailable`

            - `:too_many_requests`

            - `:execution_time_exceeded`

          - `error_message: String`

          - `type: :tool_search_tool_result_error`

            - `:tool_search_tool_result_error`

        - `class BetaToolSearchToolSearchResultBlock`

          - `tool_references: Array[BetaToolReferenceBlock]`

            - `tool_name: String`

            - `type: :tool_reference`

              - `:tool_reference`

          - `type: :tool_search_tool_search_result`

            - `:tool_search_tool_search_result`

      - `tool_use_id: String`

      - `type: :tool_search_tool_result`

        - `:tool_search_tool_result`

    - `class BetaMCPToolUseBlock`

      - `id: String`

      - `input: Hash[Symbol, untyped]`

      - `name: String`

        The name of the MCP tool

      - `server_name: String`

        The name of the MCP server

      - `type: :mcp_tool_use`

        - `:mcp_tool_use`

    - `class BetaMCPToolResultBlock`

      - `content: String | Array[BetaTextBlock]`

        - `String = String`

        - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

          - `citations: Array[BetaTextCitation]`

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

          - `text: String`

          - `type: :text`

      - `is_error: bool`

      - `tool_use_id: String`

      - `type: :mcp_tool_result`

        - `:mcp_tool_result`

    - `class BetaContainerUploadBlock`

      Response model for a file uploaded to the container.

      - `file_id: String`

      - `type: :container_upload`

        - `:container_upload`

    - `class BetaCompactionBlock`

      A compaction block returned when autocompact is triggered.

      When content is None, it indicates the compaction failed to produce a valid
      summary (e.g., malformed output from the model). Clients may round-trip
      compaction blocks with null content; the server treats them as no-ops.

      - `content: String`

        Summary of compacted content, or null if compaction failed

      - `encrypted_content: String`

        Opaque metadata from prior compaction, to be round-tripped verbatim

      - `type: :compaction`

        - `:compaction`

    - `class BetaFallbackBlock`

      Marks the point in `content` where one model's output gives way to the next.

      One block appears per hop where a preceding model actually ran this turn and
      declined. A turn routed directly by the sticky decision has no such boundary
      and carries no block — the signal for whether a fallback model served the
      response is the presence of a `fallback_message` entry in
      `usage.iterations`, not this block.

      The block is treated like a server-tool content block for streaming: it
      arrives via the standard `content_block_start` / `content_block_stop`
      pair and carries no deltas.

      - `from: BetaFallbackInfo`

        The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `:"claude-fable-5"`

              Next generation of intelligence for the hardest knowledge work and coding problems

            - `:"claude-mythos-5"`

              Most capable model for cybersecurity and biology research

            - `:"claude-opus-4-8"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-opus-4-7"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-mythos-preview"`

              New class of intelligence, strongest in coding and cybersecurity

            - `:"claude-opus-4-6"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-sonnet-4-6"`

              Best combination of speed and intelligence

            - `:"claude-haiku-4-5"`

              Fastest model with near-frontier intelligence

            - `:"claude-haiku-4-5-20251001"`

              Fastest model with near-frontier intelligence

            - `:"claude-opus-4-5"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-opus-4-5-20251101"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-sonnet-4-5"`

              High-performance model for agents and coding

            - `:"claude-sonnet-4-5-20250929"`

              High-performance model for agents and coding

            - `:"claude-opus-4-1"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-1-20250805"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-0"`

              Powerful model for complex tasks

            - `:"claude-opus-4-20250514"`

              Powerful model for complex tasks

            - `:"claude-sonnet-4-0"`

              High-performance model with extended thinking

            - `:"claude-sonnet-4-20250514"`

              High-performance model with extended thinking

            - `:"claude-3-haiku-20240307"`

              Fast and cost-effective model

          - `String = String`

      - `to: BetaFallbackInfo`

        The fallback model producing the content that follows this block. Its `model` is always the canonical id.

      - `type: :fallback`

        - `:fallback`

  - `index: Integer`

  - `type: :content_block_start`

    - `:content_block_start`

### Beta Raw Content Block Stop Event

- `class BetaRawContentBlockStopEvent`

  - `index: Integer`

  - `type: :content_block_stop`

    - `:content_block_stop`

### Beta Raw Message Delta Event

- `class BetaRawMessageDeltaEvent`

  - `context_management: BetaContextManagementResponse`

    Information about context management strategies applied during the request

    - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

      List of context management edits that were applied.

      - `class BetaClearToolUses20250919EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_tool_uses: Integer`

          Number of tool uses that were cleared.

        - `type: :clear_tool_uses_20250919`

          The type of context management edit applied.

          - `:clear_tool_uses_20250919`

      - `class BetaClearThinking20251015EditResponse`

        - `cleared_input_tokens: Integer`

          Number of input tokens cleared by this edit.

        - `cleared_thinking_turns: Integer`

          Number of thinking turns that were cleared.

        - `type: :clear_thinking_20251015`

          The type of context management edit applied.

          - `:clear_thinking_20251015`

  - `delta: Delta{ container, stop_details, stop_reason, stop_sequence}`

    - `container: BetaContainer`

      Information about the container used in the request (for the code execution tool)

      - `id: String`

        Identifier for the container used in this request

      - `expires_at: Time`

        The time at which the container will expire.

      - `skills: Array[BetaSkill]`

        Skills loaded in the container

        - `skill_id: String`

          Skill ID

        - `type: :anthropic | :custom`

          Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

          - `:anthropic`

          - `:custom`

        - `version: String`

          Skill version or 'latest' for most recent version

    - `stop_details: BetaRefusalStopDetails`

      Structured information about a refusal.

      - `category: :cyber | :bio | :reasoning_extraction`

        The policy category that triggered the refusal.

        `null` when the refusal doesn't map to a named category.

        - `:cyber`

        - `:bio`

        - `:reasoning_extraction`

      - `explanation: String`

        Human-readable explanation of the refusal.

        This text is not guaranteed to be stable. `null` when no explanation is available for the category.

      - `fallback_credit_token: String`

        Opaque code that refunds the cache-miss cost when retrying this refused
        request on the fallback model. Pass it as `fallback_credit_token` on the
        retry request. Expires 5 minutes after the refusal.

        The retry is sent either with the same request body (`system`, `messages`,
        `tools`, and other render-shaping fields), or with the same body plus one
        appended `assistant` message whose content is the partial text (with any
        trailing whitespace stripped from the final text block) and paired
        server-tool blocks from this refusal — which also authorizes that
        appended turn as an assistant-prefill continuation on models that otherwise
        disallow prefill. A token minted mid-server-tool-loop whose partial content
        was continuable may only be redeemed the second way — if a same-body retry
        is rejected with a 400 saying the token must be redeemed by continuing the
        partial response, retry the second way instead. Either way: same workspace,
        same platform; a mismatch is a 400. Resending a token for an already-warm
        prefix is permitted but yields no additional credit.

        `null` when the refused model isn't eligible for a fallback credit.

      - `fallback_has_prefill_claim: bool`

        Whether the accompanying `fallback_credit_token` may be redeemed with the
        appended-assistant retry form. Only set when `fallback_credit_token` is
        present.

        `true`: retry by resending the same request body plus one appended
        `assistant` message whose content is this response's `content` with any
        trailing whitespace stripped from the final text block and unpaired
        `tool_use` blocks omitted (the same appended-turn shape described on
        `fallback_credit_token`), with the token attached. `false`: retry by
        resending the original request body unchanged, with the token attached —
        the appended-assistant form is not available for this refusal (no
        continuable partial content, or the request uses `output_format` or a
        `tool_choice` that forces tool use). One exception: when the request used
        `output_format` or a forced `tool_choice` and the refusal arrived after
        server tools (including MCP connector tools) had already executed, the
        token may not be redeemable by either retry form; if the exact-body retry
        is then rejected with a 400 saying the token must be redeemed by
        continuing the partial response, discard the token and retry without it.

        Advisory: if an appended-assistant retry is rejected with a 400 despite
        `true`, fall back to resending the original request body with the token.

      - `recommended_model: String`

        The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

      - `type: :refusal`

        - `:refusal`

    - `stop_reason: BetaStopReason`

      - `:end_turn`

      - `:max_tokens`

      - `:stop_sequence`

      - `:tool_use`

      - `:pause_turn`

      - `:compaction`

      - `:refusal`

      - `:model_context_window_exceeded`

    - `stop_sequence: String`

  - `type: :message_delta`

    - `:message_delta`

  - `usage: BetaMessageDeltaUsage`

    Billing and rate-limit usage.

    Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

    Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

    For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

    Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

    - `cache_creation_input_tokens: Integer`

      The cumulative number of input tokens used to create the cache entry.

    - `cache_read_input_tokens: Integer`

      The cumulative number of input tokens read from the cache.

    - `input_tokens: Integer`

      The cumulative number of input tokens which were used.

    - `iterations: BetaIterationsUsage`

      Per-iteration token usage breakdown.

      Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

      - Determine which iterations exceeded long context thresholds (>=200k tokens)
      - Calculate the true context window size from the last iteration
      - Understand token accumulation across server-side tool use loops

      - `class BetaMessageIterationUsage`

        Token usage for a sampling iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

          - `ephemeral_1h_input_tokens: Integer`

            The number of input tokens used to create the 1 hour cache entry.

          - `ephemeral_5m_input_tokens: Integer`

            The number of input tokens used to create the 5 minute cache entry.

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `:"claude-fable-5"`

              Next generation of intelligence for the hardest knowledge work and coding problems

            - `:"claude-mythos-5"`

              Most capable model for cybersecurity and biology research

            - `:"claude-opus-4-8"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-opus-4-7"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-mythos-preview"`

              New class of intelligence, strongest in coding and cybersecurity

            - `:"claude-opus-4-6"`

              Frontier intelligence for long-running agents and coding

            - `:"claude-sonnet-4-6"`

              Best combination of speed and intelligence

            - `:"claude-haiku-4-5"`

              Fastest model with near-frontier intelligence

            - `:"claude-haiku-4-5-20251001"`

              Fastest model with near-frontier intelligence

            - `:"claude-opus-4-5"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-opus-4-5-20251101"`

              Premium model combining maximum intelligence with practical performance

            - `:"claude-sonnet-4-5"`

              High-performance model for agents and coding

            - `:"claude-sonnet-4-5-20250929"`

              High-performance model for agents and coding

            - `:"claude-opus-4-1"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-1-20250805"`

              Exceptional model for specialized complex tasks

            - `:"claude-opus-4-0"`

              Powerful model for complex tasks

            - `:"claude-opus-4-20250514"`

              Powerful model for complex tasks

            - `:"claude-sonnet-4-0"`

              High-performance model with extended thinking

            - `:"claude-sonnet-4-20250514"`

              High-performance model with extended thinking

            - `:"claude-3-haiku-20240307"`

              Fast and cost-effective model

          - `String = String`

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :message`

          Usage for a sampling iteration

          - `:message`

      - `class BetaCompactionIterationUsage`

        Token usage for a compaction iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :compaction`

          Usage for a compaction iteration

          - `:compaction`

      - `class BetaAdvisorMessageIterationUsage`

        Token usage for an advisor sub-inference iteration.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :advisor_message`

          Usage for an advisor sub-inference iteration

          - `:advisor_message`

      - `class BetaFallbackMessageIterationUsage`

        Token usage for the fallback-model attempt of a server-side fallback request.

        Produced in place of a `message` entry for whichever hop served the
        response. A declined hop produces the existing `message` entry. Whether
        a fallback model served the response is signalled by the presence of this
        entry in `usage.iterations`.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `type: :fallback_message`

          Usage for the fallback-model attempt that served the response

          - `:fallback_message`

    - `output_tokens: Integer`

      The cumulative number of output tokens which were used.

    - `output_tokens_details: BetaOutputTokensDetails`

      Breakdown of output tokens by category.

      `output_tokens` remains the inclusive, authoritative total used for billing.
      This object provides a read-only decomposition for observability — for example,
      how many of the billed output tokens were spent on internal reasoning that may
      have been summarized before being returned to you.

      - `thinking_tokens: Integer`

        Number of output tokens the model generated as internal reasoning, including
        the thinking-block delimiter tokens.

        Reflects the raw reasoning the model produced, not the (possibly shorter)
        summarized thinking text returned in the response body. Computed by
        re-tokenizing the raw reasoning text, so it may differ from the model's exact
        generation count by a small number of tokens. Always ≤ `output_tokens`;
        `output_tokens - thinking_tokens` approximates the non-reasoning output.

    - `server_tool_use: BetaServerToolUsage`

      The number of server tool requests.

      - `web_fetch_requests: Integer`

        The number of web fetch tool requests.

      - `web_search_requests: Integer`

        The number of web search tool requests.

### Beta Raw Message Start Event

- `class BetaRawMessageStartEvent`

  - `message: BetaMessage`

    - `id: String`

      Unique object identifier.

      The format and length of IDs may change over time.

    - `container: BetaContainer`

      Information about the container used in the request (for the code execution tool)

      - `id: String`

        Identifier for the container used in this request

      - `expires_at: Time`

        The time at which the container will expire.

      - `skills: Array[BetaSkill]`

        Skills loaded in the container

        - `skill_id: String`

          Skill ID

        - `type: :anthropic | :custom`

          Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

          - `:anthropic`

          - `:custom`

        - `version: String`

          Skill version or 'latest' for most recent version

    - `content: Array[BetaContentBlock]`

      Content generated by the model.

      This is an array of content blocks, each of which has a `type` that determines its shape.

      Example:

      ```json
      [{"type": "text", "text": "Hi, I'm Claude."}]
      ```

      If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

      For example, if the input `messages` were:

      ```json
      [
        {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
        {"role": "assistant", "content": "The best answer is ("}
      ]
      ```

      Then the response `content` might be:

      ```json
      [{"type": "text", "text": "B)"}]
      ```

      - `class BetaTextBlock`

        - `citations: Array[BetaTextCitation]`

          Citations supporting the text block.

          The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

          - `class BetaCitationCharLocation`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `file_id: String`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocation`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `file_id: String`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocation`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `file_id: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationsWebSearchResultLocation`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocation`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

        - `text: String`

        - `type: :text`

          - `:text`

      - `class BetaThinkingBlock`

        - `signature: String`

        - `thinking: String`

        - `type: :thinking`

          - `:thinking`

      - `class BetaRedactedThinkingBlock`

        - `data: String`

        - `type: :redacted_thinking`

          - `:redacted_thinking`

      - `class BetaToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `type: :tool_use`

          - `:tool_use`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

            - `type: :direct`

              - `:direct`

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

            - `tool_id: String`

            - `type: :code_execution_20250825`

              - `:code_execution_20250825`

          - `class BetaServerToolCaller20260120`

            - `tool_id: String`

            - `type: :code_execution_20260120`

              - `:code_execution_20260120`

      - `class BetaServerToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: :advisor | :web_search | :web_fetch | 5 more`

          - `:advisor`

          - `:web_search`

          - `:web_fetch`

          - `:code_execution`

          - `:bash_code_execution`

          - `:text_editor_code_execution`

          - `:tool_search_tool_regex`

          - `:tool_search_tool_bm25`

        - `type: :server_tool_use`

          - `:server_tool_use`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebSearchToolResultBlock`

        - `content: BetaWebSearchToolResultBlockContent`

          - `class BetaWebSearchToolResultError`

            - `error_code: BetaWebSearchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:max_uses_exceeded`

              - `:too_many_requests`

              - `:query_too_long`

              - `:request_too_large`

            - `type: :web_search_tool_result_error`

              - `:web_search_tool_result_error`

          - `UnionMember1 = Array[BetaWebSearchResultBlock]`

            - `encrypted_content: String`

            - `page_age: String`

            - `title: String`

            - `type: :web_search_result`

              - `:web_search_result`

            - `url: String`

        - `tool_use_id: String`

        - `type: :web_search_tool_result`

          - `:web_search_tool_result`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebFetchToolResultBlock`

        - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

          - `class BetaWebFetchToolResultErrorBlock`

            - `error_code: BetaWebFetchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:url_too_long`

              - `:url_not_allowed`

              - `:url_not_in_prior_context`

              - `:url_not_accessible`

              - `:unsupported_content_type`

              - `:too_many_requests`

              - `:max_uses_exceeded`

              - `:unavailable`

            - `type: :web_fetch_tool_result_error`

              - `:web_fetch_tool_result_error`

          - `class BetaWebFetchBlock`

            - `content: BetaDocumentBlock`

              - `citations: BetaCitationConfig`

                Citation configuration for the document

                - `enabled: bool`

              - `source: BetaBase64PDFSource | BetaPlainTextSource`

                - `class BetaBase64PDFSource`

                  - `data: String`

                  - `media_type: :"application/pdf"`

                    - `:"application/pdf"`

                  - `type: :base64`

                    - `:base64`

                - `class BetaPlainTextSource`

                  - `data: String`

                  - `media_type: :"text/plain"`

                    - `:"text/plain"`

                  - `type: :text`

                    - `:text`

              - `title: String`

                The title of the document

              - `type: :document`

                - `:document`

            - `retrieved_at: String`

              ISO 8601 timestamp when the content was retrieved

            - `type: :web_fetch_result`

              - `:web_fetch_result`

            - `url: String`

              Fetched content URL

        - `tool_use_id: String`

        - `type: :web_fetch_tool_result`

          - `:web_fetch_tool_result`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaAdvisorToolResultBlock`

        - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

          - `class BetaAdvisorToolResultError`

            - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

              - `:max_uses_exceeded`

              - `:prompt_too_long`

              - `:too_many_requests`

              - `:overloaded`

              - `:unavailable`

              - `:execution_time_exceeded`

              - `:model_not_found`

            - `type: :advisor_tool_result_error`

              - `:advisor_tool_result_error`

          - `class BetaAdvisorResultBlock`

            - `stop_reason: String`

              The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

            - `text: String`

            - `type: :advisor_result`

              - `:advisor_result`

          - `class BetaAdvisorRedactedResultBlock`

            - `encrypted_content: String`

              Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

            - `stop_reason: String`

              The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

            - `type: :advisor_redacted_result`

              - `:advisor_redacted_result`

        - `tool_use_id: String`

        - `type: :advisor_tool_result`

          - `:advisor_tool_result`

      - `class BetaCodeExecutionToolResultBlock`

        - `content: BetaCodeExecutionToolResultBlockContent`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `class BetaCodeExecutionToolResultError`

            - `error_code: BetaCodeExecutionToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :code_execution_tool_result_error`

              - `:code_execution_tool_result_error`

          - `class BetaCodeExecutionResultBlock`

            - `content: Array[BetaCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :code_execution_output`

                - `:code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :code_execution_result`

              - `:code_execution_result`

          - `class BetaEncryptedCodeExecutionResultBlock`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `content: Array[BetaCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :code_execution_output`

            - `encrypted_stdout: String`

            - `return_code: Integer`

            - `stderr: String`

            - `type: :encrypted_code_execution_result`

              - `:encrypted_code_execution_result`

        - `tool_use_id: String`

        - `type: :code_execution_tool_result`

          - `:code_execution_tool_result`

      - `class BetaBashCodeExecutionToolResultBlock`

        - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

          - `class BetaBashCodeExecutionToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:output_file_too_large`

            - `type: :bash_code_execution_tool_result_error`

              - `:bash_code_execution_tool_result_error`

          - `class BetaBashCodeExecutionResultBlock`

            - `content: Array[BetaBashCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :bash_code_execution_output`

                - `:bash_code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :bash_code_execution_result`

              - `:bash_code_execution_result`

        - `tool_use_id: String`

        - `type: :bash_code_execution_tool_result`

          - `:bash_code_execution_tool_result`

      - `class BetaTextEditorCodeExecutionToolResultBlock`

        - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

          - `class BetaTextEditorCodeExecutionToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:file_not_found`

            - `error_message: String`

            - `type: :text_editor_code_execution_tool_result_error`

              - `:text_editor_code_execution_tool_result_error`

          - `class BetaTextEditorCodeExecutionViewResultBlock`

            - `content: String`

            - `file_type: :text | :image | :pdf`

              - `:text`

              - `:image`

              - `:pdf`

            - `num_lines: Integer`

            - `start_line: Integer`

            - `total_lines: Integer`

            - `type: :text_editor_code_execution_view_result`

              - `:text_editor_code_execution_view_result`

          - `class BetaTextEditorCodeExecutionCreateResultBlock`

            - `is_file_update: bool`

            - `type: :text_editor_code_execution_create_result`

              - `:text_editor_code_execution_create_result`

          - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

            - `lines: Array[String]`

            - `new_lines: Integer`

            - `new_start: Integer`

            - `old_lines: Integer`

            - `old_start: Integer`

            - `type: :text_editor_code_execution_str_replace_result`

              - `:text_editor_code_execution_str_replace_result`

        - `tool_use_id: String`

        - `type: :text_editor_code_execution_tool_result`

          - `:text_editor_code_execution_tool_result`

      - `class BetaToolSearchToolResultBlock`

        - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

          - `class BetaToolSearchToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `error_message: String`

            - `type: :tool_search_tool_result_error`

              - `:tool_search_tool_result_error`

          - `class BetaToolSearchToolSearchResultBlock`

            - `tool_references: Array[BetaToolReferenceBlock]`

              - `tool_name: String`

              - `type: :tool_reference`

                - `:tool_reference`

            - `type: :tool_search_tool_search_result`

              - `:tool_search_tool_search_result`

        - `tool_use_id: String`

        - `type: :tool_search_tool_result`

          - `:tool_search_tool_result`

      - `class BetaMCPToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

          The name of the MCP tool

        - `server_name: String`

          The name of the MCP server

        - `type: :mcp_tool_use`

          - `:mcp_tool_use`

      - `class BetaMCPToolResultBlock`

        - `content: String | Array[BetaTextBlock]`

          - `String = String`

          - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

            - `citations: Array[BetaTextCitation]`

              Citations supporting the text block.

              The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

            - `text: String`

            - `type: :text`

        - `is_error: bool`

        - `tool_use_id: String`

        - `type: :mcp_tool_result`

          - `:mcp_tool_result`

      - `class BetaContainerUploadBlock`

        Response model for a file uploaded to the container.

        - `file_id: String`

        - `type: :container_upload`

          - `:container_upload`

      - `class BetaCompactionBlock`

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid
        summary (e.g., malformed output from the model). Clients may round-trip
        compaction blocks with null content; the server treats them as no-ops.

        - `content: String`

          Summary of compacted content, or null if compaction failed

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

        - `type: :compaction`

          - `:compaction`

      - `class BetaFallbackBlock`

        Marks the point in `content` where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and
        declined. A turn routed directly by the sticky decision has no such boundary
        and carries no block — the signal for whether a fallback model served the
        response is the presence of a `fallback_message` entry in
        `usage.iterations`, not this block.

        The block is treated like a server-tool content block for streaming: it
        arrives via the standard `content_block_start` / `content_block_stop`
        pair and carries no deltas.

        - `from: BetaFallbackInfo`

          The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `:"claude-fable-5"`

                Next generation of intelligence for the hardest knowledge work and coding problems

              - `:"claude-mythos-5"`

                Most capable model for cybersecurity and biology research

              - `:"claude-opus-4-8"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-opus-4-7"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-mythos-preview"`

                New class of intelligence, strongest in coding and cybersecurity

              - `:"claude-opus-4-6"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-sonnet-4-6"`

                Best combination of speed and intelligence

              - `:"claude-haiku-4-5"`

                Fastest model with near-frontier intelligence

              - `:"claude-haiku-4-5-20251001"`

                Fastest model with near-frontier intelligence

              - `:"claude-opus-4-5"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-opus-4-5-20251101"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-sonnet-4-5"`

                High-performance model for agents and coding

              - `:"claude-sonnet-4-5-20250929"`

                High-performance model for agents and coding

              - `:"claude-opus-4-1"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-1-20250805"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-0"`

                Powerful model for complex tasks

              - `:"claude-opus-4-20250514"`

                Powerful model for complex tasks

              - `:"claude-sonnet-4-0"`

                High-performance model with extended thinking

              - `:"claude-sonnet-4-20250514"`

                High-performance model with extended thinking

              - `:"claude-3-haiku-20240307"`

                Fast and cost-effective model

            - `String = String`

        - `to: BetaFallbackInfo`

          The fallback model producing the content that follows this block. Its `model` is always the canonical id.

        - `type: :fallback`

          - `:fallback`

    - `context_management: BetaContextManagementResponse`

      Context management response.

      Information about context management strategies applied during the request.

      - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

        List of context management edits that were applied.

        - `class BetaClearToolUses20250919EditResponse`

          - `cleared_input_tokens: Integer`

            Number of input tokens cleared by this edit.

          - `cleared_tool_uses: Integer`

            Number of tool uses that were cleared.

          - `type: :clear_tool_uses_20250919`

            The type of context management edit applied.

            - `:clear_tool_uses_20250919`

        - `class BetaClearThinking20251015EditResponse`

          - `cleared_input_tokens: Integer`

            Number of input tokens cleared by this edit.

          - `cleared_thinking_turns: Integer`

            Number of thinking turns that were cleared.

          - `type: :clear_thinking_20251015`

            The type of context management edit applied.

            - `:clear_thinking_20251015`

    - `diagnostics: BetaDiagnostics`

      Response envelope for request-level diagnostics. Present (possibly
      null) whenever the caller supplied `diagnostics` on the request.

      - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

        Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

        - `class BetaCacheMissModelChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :model_changed`

            - `:model_changed`

        - `class BetaCacheMissSystemChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :system_changed`

            - `:system_changed`

        - `class BetaCacheMissToolsChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :tools_changed`

            - `:tools_changed`

        - `class BetaCacheMissMessagesChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :messages_changed`

            - `:messages_changed`

        - `class BetaCacheMissPreviousMessageNotFound`

          - `type: :previous_message_not_found`

            - `:previous_message_not_found`

        - `class BetaCacheMissUnavailable`

          - `type: :unavailable`

            - `:unavailable`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `role: :assistant`

      Conversational role of the generated message.

      This will always be `"assistant"`.

      - `:assistant`

    - `stop_details: BetaRefusalStopDetails`

      Structured information about a refusal.

      - `category: :cyber | :bio | :reasoning_extraction`

        The policy category that triggered the refusal.

        `null` when the refusal doesn't map to a named category.

        - `:cyber`

        - `:bio`

        - `:reasoning_extraction`

      - `explanation: String`

        Human-readable explanation of the refusal.

        This text is not guaranteed to be stable. `null` when no explanation is available for the category.

      - `fallback_credit_token: String`

        Opaque code that refunds the cache-miss cost when retrying this refused
        request on the fallback model. Pass it as `fallback_credit_token` on the
        retry request. Expires 5 minutes after the refusal.

        The retry is sent either with the same request body (`system`, `messages`,
        `tools`, and other render-shaping fields), or with the same body plus one
        appended `assistant` message whose content is the partial text (with any
        trailing whitespace stripped from the final text block) and paired
        server-tool blocks from this refusal — which also authorizes that
        appended turn as an assistant-prefill continuation on models that otherwise
        disallow prefill. A token minted mid-server-tool-loop whose partial content
        was continuable may only be redeemed the second way — if a same-body retry
        is rejected with a 400 saying the token must be redeemed by continuing the
        partial response, retry the second way instead. Either way: same workspace,
        same platform; a mismatch is a 400. Resending a token for an already-warm
        prefix is permitted but yields no additional credit.

        `null` when the refused model isn't eligible for a fallback credit.

      - `fallback_has_prefill_claim: bool`

        Whether the accompanying `fallback_credit_token` may be redeemed with the
        appended-assistant retry form. Only set when `fallback_credit_token` is
        present.

        `true`: retry by resending the same request body plus one appended
        `assistant` message whose content is this response's `content` with any
        trailing whitespace stripped from the final text block and unpaired
        `tool_use` blocks omitted (the same appended-turn shape described on
        `fallback_credit_token`), with the token attached. `false`: retry by
        resending the original request body unchanged, with the token attached —
        the appended-assistant form is not available for this refusal (no
        continuable partial content, or the request uses `output_format` or a
        `tool_choice` that forces tool use). One exception: when the request used
        `output_format` or a forced `tool_choice` and the refusal arrived after
        server tools (including MCP connector tools) had already executed, the
        token may not be redeemable by either retry form; if the exact-body retry
        is then rejected with a 400 saying the token must be redeemed by
        continuing the partial response, discard the token and retry without it.

        Advisory: if an appended-assistant retry is rejected with a 400 despite
        `true`, fall back to resending the original request body with the token.

      - `recommended_model: String`

        The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

      - `type: :refusal`

        - `:refusal`

    - `stop_reason: BetaStopReason`

      The reason that we stopped.

      This may be one the following values:

      * `"end_turn"`: the model reached a natural stopping point
      * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
      * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
      * `"tool_use"`: the model invoked one or more tools
      * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
      * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

      In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

      - `:end_turn`

      - `:max_tokens`

      - `:stop_sequence`

      - `:tool_use`

      - `:pause_turn`

      - `:compaction`

      - `:refusal`

      - `:model_context_window_exceeded`

    - `stop_sequence: String`

      Which custom stop sequence was generated, if any.

      This value will be a non-null string if one of your custom stop sequences was generated.

    - `type: :message`

      Object type.

      For Messages, this is always `"message"`.

      - `:message`

    - `usage: BetaUsage`

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

      For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

        - `ephemeral_1h_input_tokens: Integer`

          The number of input tokens used to create the 1 hour cache entry.

        - `ephemeral_5m_input_tokens: Integer`

          The number of input tokens used to create the 5 minute cache entry.

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `inference_geo: String`

        The geographic region where inference was performed for this request.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `iterations: BetaIterationsUsage`

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

        - Determine which iterations exceeded long context thresholds (>=200k tokens)
        - Calculate the true context window size from the last iteration
        - Understand token accumulation across server-side tool use loops

        - `class BetaMessageIterationUsage`

          Token usage for a sampling iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :message`

            Usage for a sampling iteration

            - `:message`

        - `class BetaCompactionIterationUsage`

          Token usage for a compaction iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :compaction`

            Usage for a compaction iteration

            - `:compaction`

        - `class BetaAdvisorMessageIterationUsage`

          Token usage for an advisor sub-inference iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :advisor_message`

            Usage for an advisor sub-inference iteration

            - `:advisor_message`

        - `class BetaFallbackMessageIterationUsage`

          Token usage for the fallback-model attempt of a server-side fallback request.

          Produced in place of a `message` entry for whichever hop served the
          response. A declined hop produces the existing `message` entry. Whether
          a fallback model served the response is signalled by the presence of this
          entry in `usage.iterations`.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :fallback_message`

            Usage for the fallback-model attempt that served the response

            - `:fallback_message`

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `output_tokens_details: BetaOutputTokensDetails`

        Breakdown of output tokens by category.

        `output_tokens` remains the inclusive, authoritative total used for billing.
        This object provides a read-only decomposition for observability — for example,
        how many of the billed output tokens were spent on internal reasoning that may
        have been summarized before being returned to you.

        - `thinking_tokens: Integer`

          Number of output tokens the model generated as internal reasoning, including
          the thinking-block delimiter tokens.

          Reflects the raw reasoning the model produced, not the (possibly shorter)
          summarized thinking text returned in the response body. Computed by
          re-tokenizing the raw reasoning text, so it may differ from the model's exact
          generation count by a small number of tokens. Always ≤ `output_tokens`;
          `output_tokens - thinking_tokens` approximates the non-reasoning output.

      - `server_tool_use: BetaServerToolUsage`

        The number of server tool requests.

        - `web_fetch_requests: Integer`

          The number of web fetch tool requests.

        - `web_search_requests: Integer`

          The number of web search tool requests.

      - `service_tier: :standard | :priority | :batch`

        If the request used the priority, standard, or batch tier.

        - `:standard`

        - `:priority`

        - `:batch`

      - `speed: :standard | :fast`

        The inference speed mode used for this request.

        - `:standard`

        - `:fast`

  - `type: :message_start`

    - `:message_start`

### Beta Raw Message Stop Event

- `class BetaRawMessageStopEvent`

  - `type: :message_stop`

    - `:message_stop`

### Beta Raw Message Stream Event

- `BetaRawMessageStreamEvent = BetaRawMessageStartEvent | BetaRawMessageDeltaEvent | BetaRawMessageStopEvent | 3 more`

  - `class BetaRawMessageStartEvent`

    - `message: BetaMessage`

      - `id: String`

        Unique object identifier.

        The format and length of IDs may change over time.

      - `container: BetaContainer`

        Information about the container used in the request (for the code execution tool)

        - `id: String`

          Identifier for the container used in this request

        - `expires_at: Time`

          The time at which the container will expire.

        - `skills: Array[BetaSkill]`

          Skills loaded in the container

          - `skill_id: String`

            Skill ID

          - `type: :anthropic | :custom`

            Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

            - `:anthropic`

            - `:custom`

          - `version: String`

            Skill version or 'latest' for most recent version

      - `content: Array[BetaContentBlock]`

        Content generated by the model.

        This is an array of content blocks, each of which has a `type` that determines its shape.

        Example:

        ```json
        [{"type": "text", "text": "Hi, I'm Claude."}]
        ```

        If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

        For example, if the input `messages` were:

        ```json
        [
          {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
          {"role": "assistant", "content": "The best answer is ("}
        ]
        ```

        Then the response `content` might be:

        ```json
        [{"type": "text", "text": "B)"}]
        ```

        - `class BetaTextBlock`

          - `citations: Array[BetaTextCitation]`

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

            - `class BetaCitationCharLocation`

              - `cited_text: String`

              - `document_index: Integer`

              - `document_title: String`

              - `end_char_index: Integer`

              - `file_id: String`

              - `start_char_index: Integer`

              - `type: :char_location`

                - `:char_location`

            - `class BetaCitationPageLocation`

              - `cited_text: String`

              - `document_index: Integer`

              - `document_title: String`

              - `end_page_number: Integer`

              - `file_id: String`

              - `start_page_number: Integer`

              - `type: :page_location`

                - `:page_location`

            - `class BetaCitationContentBlockLocation`

              - `cited_text: String`

                The full text of the cited block range, concatenated.

                Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              - `document_index: Integer`

              - `document_title: String`

              - `end_block_index: Integer`

                Exclusive 0-based end index of the cited block range in the source's `content` array.

                Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

              - `file_id: String`

              - `start_block_index: Integer`

                0-based index of the first cited block in the source's `content` array.

              - `type: :content_block_location`

                - `:content_block_location`

            - `class BetaCitationsWebSearchResultLocation`

              - `cited_text: String`

              - `encrypted_index: String`

              - `title: String`

              - `type: :web_search_result_location`

                - `:web_search_result_location`

              - `url: String`

            - `class BetaCitationSearchResultLocation`

              - `cited_text: String`

                The full text of the cited block range, concatenated.

                Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              - `end_block_index: Integer`

                Exclusive 0-based end index of the cited block range in the source's `content` array.

                Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

              - `search_result_index: Integer`

                0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                Counted separately from `document_index`; server-side web search results are not included in this count.

              - `source: String`

              - `start_block_index: Integer`

                0-based index of the first cited block in the source's `content` array.

              - `title: String`

              - `type: :search_result_location`

                - `:search_result_location`

          - `text: String`

          - `type: :text`

            - `:text`

        - `class BetaThinkingBlock`

          - `signature: String`

          - `thinking: String`

          - `type: :thinking`

            - `:thinking`

        - `class BetaRedactedThinkingBlock`

          - `data: String`

          - `type: :redacted_thinking`

            - `:redacted_thinking`

        - `class BetaToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: String`

          - `type: :tool_use`

            - `:tool_use`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

              - `type: :direct`

                - `:direct`

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

              - `tool_id: String`

              - `type: :code_execution_20250825`

                - `:code_execution_20250825`

            - `class BetaServerToolCaller20260120`

              - `tool_id: String`

              - `type: :code_execution_20260120`

                - `:code_execution_20260120`

        - `class BetaServerToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: :advisor | :web_search | :web_fetch | 5 more`

            - `:advisor`

            - `:web_search`

            - `:web_fetch`

            - `:code_execution`

            - `:bash_code_execution`

            - `:text_editor_code_execution`

            - `:tool_search_tool_regex`

            - `:tool_search_tool_bm25`

          - `type: :server_tool_use`

            - `:server_tool_use`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaWebSearchToolResultBlock`

          - `content: BetaWebSearchToolResultBlockContent`

            - `class BetaWebSearchToolResultError`

              - `error_code: BetaWebSearchToolResultErrorCode`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:max_uses_exceeded`

                - `:too_many_requests`

                - `:query_too_long`

                - `:request_too_large`

              - `type: :web_search_tool_result_error`

                - `:web_search_tool_result_error`

            - `UnionMember1 = Array[BetaWebSearchResultBlock]`

              - `encrypted_content: String`

              - `page_age: String`

              - `title: String`

              - `type: :web_search_result`

                - `:web_search_result`

              - `url: String`

          - `tool_use_id: String`

          - `type: :web_search_tool_result`

            - `:web_search_tool_result`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaWebFetchToolResultBlock`

          - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

            - `class BetaWebFetchToolResultErrorBlock`

              - `error_code: BetaWebFetchToolResultErrorCode`

                - `:invalid_tool_input`

                - `:url_too_long`

                - `:url_not_allowed`

                - `:url_not_in_prior_context`

                - `:url_not_accessible`

                - `:unsupported_content_type`

                - `:too_many_requests`

                - `:max_uses_exceeded`

                - `:unavailable`

              - `type: :web_fetch_tool_result_error`

                - `:web_fetch_tool_result_error`

            - `class BetaWebFetchBlock`

              - `content: BetaDocumentBlock`

                - `citations: BetaCitationConfig`

                  Citation configuration for the document

                  - `enabled: bool`

                - `source: BetaBase64PDFSource | BetaPlainTextSource`

                  - `class BetaBase64PDFSource`

                    - `data: String`

                    - `media_type: :"application/pdf"`

                      - `:"application/pdf"`

                    - `type: :base64`

                      - `:base64`

                  - `class BetaPlainTextSource`

                    - `data: String`

                    - `media_type: :"text/plain"`

                      - `:"text/plain"`

                    - `type: :text`

                      - `:text`

                - `title: String`

                  The title of the document

                - `type: :document`

                  - `:document`

              - `retrieved_at: String`

                ISO 8601 timestamp when the content was retrieved

              - `type: :web_fetch_result`

                - `:web_fetch_result`

              - `url: String`

                Fetched content URL

          - `tool_use_id: String`

          - `type: :web_fetch_tool_result`

            - `:web_fetch_tool_result`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaAdvisorToolResultBlock`

          - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

            - `class BetaAdvisorToolResultError`

              - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

                - `:max_uses_exceeded`

                - `:prompt_too_long`

                - `:too_many_requests`

                - `:overloaded`

                - `:unavailable`

                - `:execution_time_exceeded`

                - `:model_not_found`

              - `type: :advisor_tool_result_error`

                - `:advisor_tool_result_error`

            - `class BetaAdvisorResultBlock`

              - `stop_reason: String`

                The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

              - `text: String`

              - `type: :advisor_result`

                - `:advisor_result`

            - `class BetaAdvisorRedactedResultBlock`

              - `encrypted_content: String`

                Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

              - `stop_reason: String`

                The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

              - `type: :advisor_redacted_result`

                - `:advisor_redacted_result`

          - `tool_use_id: String`

          - `type: :advisor_tool_result`

            - `:advisor_tool_result`

        - `class BetaCodeExecutionToolResultBlock`

          - `content: BetaCodeExecutionToolResultBlockContent`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `class BetaCodeExecutionToolResultError`

              - `error_code: BetaCodeExecutionToolResultErrorCode`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

              - `type: :code_execution_tool_result_error`

                - `:code_execution_tool_result_error`

            - `class BetaCodeExecutionResultBlock`

              - `content: Array[BetaCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :code_execution_output`

                  - `:code_execution_output`

              - `return_code: Integer`

              - `stderr: String`

              - `stdout: String`

              - `type: :code_execution_result`

                - `:code_execution_result`

            - `class BetaEncryptedCodeExecutionResultBlock`

              Code execution result with encrypted stdout for PFC + web_search results.

              - `content: Array[BetaCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :code_execution_output`

              - `encrypted_stdout: String`

              - `return_code: Integer`

              - `stderr: String`

              - `type: :encrypted_code_execution_result`

                - `:encrypted_code_execution_result`

          - `tool_use_id: String`

          - `type: :code_execution_tool_result`

            - `:code_execution_tool_result`

        - `class BetaBashCodeExecutionToolResultBlock`

          - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

            - `class BetaBashCodeExecutionToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

                - `:output_file_too_large`

              - `type: :bash_code_execution_tool_result_error`

                - `:bash_code_execution_tool_result_error`

            - `class BetaBashCodeExecutionResultBlock`

              - `content: Array[BetaBashCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :bash_code_execution_output`

                  - `:bash_code_execution_output`

              - `return_code: Integer`

              - `stderr: String`

              - `stdout: String`

              - `type: :bash_code_execution_result`

                - `:bash_code_execution_result`

          - `tool_use_id: String`

          - `type: :bash_code_execution_tool_result`

            - `:bash_code_execution_tool_result`

        - `class BetaTextEditorCodeExecutionToolResultBlock`

          - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

            - `class BetaTextEditorCodeExecutionToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

                - `:file_not_found`

              - `error_message: String`

              - `type: :text_editor_code_execution_tool_result_error`

                - `:text_editor_code_execution_tool_result_error`

            - `class BetaTextEditorCodeExecutionViewResultBlock`

              - `content: String`

              - `file_type: :text | :image | :pdf`

                - `:text`

                - `:image`

                - `:pdf`

              - `num_lines: Integer`

              - `start_line: Integer`

              - `total_lines: Integer`

              - `type: :text_editor_code_execution_view_result`

                - `:text_editor_code_execution_view_result`

            - `class BetaTextEditorCodeExecutionCreateResultBlock`

              - `is_file_update: bool`

              - `type: :text_editor_code_execution_create_result`

                - `:text_editor_code_execution_create_result`

            - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

              - `lines: Array[String]`

              - `new_lines: Integer`

              - `new_start: Integer`

              - `old_lines: Integer`

              - `old_start: Integer`

              - `type: :text_editor_code_execution_str_replace_result`

                - `:text_editor_code_execution_str_replace_result`

          - `tool_use_id: String`

          - `type: :text_editor_code_execution_tool_result`

            - `:text_editor_code_execution_tool_result`

        - `class BetaToolSearchToolResultBlock`

          - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

            - `class BetaToolSearchToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

              - `error_message: String`

              - `type: :tool_search_tool_result_error`

                - `:tool_search_tool_result_error`

            - `class BetaToolSearchToolSearchResultBlock`

              - `tool_references: Array[BetaToolReferenceBlock]`

                - `tool_name: String`

                - `type: :tool_reference`

                  - `:tool_reference`

              - `type: :tool_search_tool_search_result`

                - `:tool_search_tool_search_result`

          - `tool_use_id: String`

          - `type: :tool_search_tool_result`

            - `:tool_search_tool_result`

        - `class BetaMCPToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: String`

            The name of the MCP tool

          - `server_name: String`

            The name of the MCP server

          - `type: :mcp_tool_use`

            - `:mcp_tool_use`

        - `class BetaMCPToolResultBlock`

          - `content: String | Array[BetaTextBlock]`

            - `String = String`

            - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

              - `citations: Array[BetaTextCitation]`

                Citations supporting the text block.

                The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

              - `text: String`

              - `type: :text`

          - `is_error: bool`

          - `tool_use_id: String`

          - `type: :mcp_tool_result`

            - `:mcp_tool_result`

        - `class BetaContainerUploadBlock`

          Response model for a file uploaded to the container.

          - `file_id: String`

          - `type: :container_upload`

            - `:container_upload`

        - `class BetaCompactionBlock`

          A compaction block returned when autocompact is triggered.

          When content is None, it indicates the compaction failed to produce a valid
          summary (e.g., malformed output from the model). Clients may round-trip
          compaction blocks with null content; the server treats them as no-ops.

          - `content: String`

            Summary of compacted content, or null if compaction failed

          - `encrypted_content: String`

            Opaque metadata from prior compaction, to be round-tripped verbatim

          - `type: :compaction`

            - `:compaction`

        - `class BetaFallbackBlock`

          Marks the point in `content` where one model's output gives way to the next.

          One block appears per hop where a preceding model actually ran this turn and
          declined. A turn routed directly by the sticky decision has no such boundary
          and carries no block — the signal for whether a fallback model served the
          response is the presence of a `fallback_message` entry in
          `usage.iterations`, not this block.

          The block is treated like a server-tool content block for streaming: it
          arrives via the standard `content_block_start` / `content_block_stop`
          pair and carries no deltas.

          - `from: BetaFallbackInfo`

            The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                - `:"claude-fable-5"`

                  Next generation of intelligence for the hardest knowledge work and coding problems

                - `:"claude-mythos-5"`

                  Most capable model for cybersecurity and biology research

                - `:"claude-opus-4-8"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-opus-4-7"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-mythos-preview"`

                  New class of intelligence, strongest in coding and cybersecurity

                - `:"claude-opus-4-6"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-sonnet-4-6"`

                  Best combination of speed and intelligence

                - `:"claude-haiku-4-5"`

                  Fastest model with near-frontier intelligence

                - `:"claude-haiku-4-5-20251001"`

                  Fastest model with near-frontier intelligence

                - `:"claude-opus-4-5"`

                  Premium model combining maximum intelligence with practical performance

                - `:"claude-opus-4-5-20251101"`

                  Premium model combining maximum intelligence with practical performance

                - `:"claude-sonnet-4-5"`

                  High-performance model for agents and coding

                - `:"claude-sonnet-4-5-20250929"`

                  High-performance model for agents and coding

                - `:"claude-opus-4-1"`

                  Exceptional model for specialized complex tasks

                - `:"claude-opus-4-1-20250805"`

                  Exceptional model for specialized complex tasks

                - `:"claude-opus-4-0"`

                  Powerful model for complex tasks

                - `:"claude-opus-4-20250514"`

                  Powerful model for complex tasks

                - `:"claude-sonnet-4-0"`

                  High-performance model with extended thinking

                - `:"claude-sonnet-4-20250514"`

                  High-performance model with extended thinking

                - `:"claude-3-haiku-20240307"`

                  Fast and cost-effective model

              - `String = String`

          - `to: BetaFallbackInfo`

            The fallback model producing the content that follows this block. Its `model` is always the canonical id.

          - `type: :fallback`

            - `:fallback`

      - `context_management: BetaContextManagementResponse`

        Context management response.

        Information about context management strategies applied during the request.

        - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

          List of context management edits that were applied.

          - `class BetaClearToolUses20250919EditResponse`

            - `cleared_input_tokens: Integer`

              Number of input tokens cleared by this edit.

            - `cleared_tool_uses: Integer`

              Number of tool uses that were cleared.

            - `type: :clear_tool_uses_20250919`

              The type of context management edit applied.

              - `:clear_tool_uses_20250919`

          - `class BetaClearThinking20251015EditResponse`

            - `cleared_input_tokens: Integer`

              Number of input tokens cleared by this edit.

            - `cleared_thinking_turns: Integer`

              Number of thinking turns that were cleared.

            - `type: :clear_thinking_20251015`

              The type of context management edit applied.

              - `:clear_thinking_20251015`

      - `diagnostics: BetaDiagnostics`

        Response envelope for request-level diagnostics. Present (possibly
        null) whenever the caller supplied `diagnostics` on the request.

        - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

          Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

          - `class BetaCacheMissModelChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :model_changed`

              - `:model_changed`

          - `class BetaCacheMissSystemChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :system_changed`

              - `:system_changed`

          - `class BetaCacheMissToolsChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :tools_changed`

              - `:tools_changed`

          - `class BetaCacheMissMessagesChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :messages_changed`

              - `:messages_changed`

          - `class BetaCacheMissPreviousMessageNotFound`

            - `type: :previous_message_not_found`

              - `:previous_message_not_found`

          - `class BetaCacheMissUnavailable`

            - `type: :unavailable`

              - `:unavailable`

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `role: :assistant`

        Conversational role of the generated message.

        This will always be `"assistant"`.

        - `:assistant`

      - `stop_details: BetaRefusalStopDetails`

        Structured information about a refusal.

        - `category: :cyber | :bio | :reasoning_extraction`

          The policy category that triggered the refusal.

          `null` when the refusal doesn't map to a named category.

          - `:cyber`

          - `:bio`

          - `:reasoning_extraction`

        - `explanation: String`

          Human-readable explanation of the refusal.

          This text is not guaranteed to be stable. `null` when no explanation is available for the category.

        - `fallback_credit_token: String`

          Opaque code that refunds the cache-miss cost when retrying this refused
          request on the fallback model. Pass it as `fallback_credit_token` on the
          retry request. Expires 5 minutes after the refusal.

          The retry is sent either with the same request body (`system`, `messages`,
          `tools`, and other render-shaping fields), or with the same body plus one
          appended `assistant` message whose content is the partial text (with any
          trailing whitespace stripped from the final text block) and paired
          server-tool blocks from this refusal — which also authorizes that
          appended turn as an assistant-prefill continuation on models that otherwise
          disallow prefill. A token minted mid-server-tool-loop whose partial content
          was continuable may only be redeemed the second way — if a same-body retry
          is rejected with a 400 saying the token must be redeemed by continuing the
          partial response, retry the second way instead. Either way: same workspace,
          same platform; a mismatch is a 400. Resending a token for an already-warm
          prefix is permitted but yields no additional credit.

          `null` when the refused model isn't eligible for a fallback credit.

        - `fallback_has_prefill_claim: bool`

          Whether the accompanying `fallback_credit_token` may be redeemed with the
          appended-assistant retry form. Only set when `fallback_credit_token` is
          present.

          `true`: retry by resending the same request body plus one appended
          `assistant` message whose content is this response's `content` with any
          trailing whitespace stripped from the final text block and unpaired
          `tool_use` blocks omitted (the same appended-turn shape described on
          `fallback_credit_token`), with the token attached. `false`: retry by
          resending the original request body unchanged, with the token attached —
          the appended-assistant form is not available for this refusal (no
          continuable partial content, or the request uses `output_format` or a
          `tool_choice` that forces tool use). One exception: when the request used
          `output_format` or a forced `tool_choice` and the refusal arrived after
          server tools (including MCP connector tools) had already executed, the
          token may not be redeemable by either retry form; if the exact-body retry
          is then rejected with a 400 saying the token must be redeemed by
          continuing the partial response, discard the token and retry without it.

          Advisory: if an appended-assistant retry is rejected with a 400 despite
          `true`, fall back to resending the original request body with the token.

        - `recommended_model: String`

          The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

        - `type: :refusal`

          - `:refusal`

      - `stop_reason: BetaStopReason`

        The reason that we stopped.

        This may be one the following values:

        * `"end_turn"`: the model reached a natural stopping point
        * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
        * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
        * `"tool_use"`: the model invoked one or more tools
        * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
        * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

        In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

        - `:end_turn`

        - `:max_tokens`

        - `:stop_sequence`

        - `:tool_use`

        - `:pause_turn`

        - `:compaction`

        - `:refusal`

        - `:model_context_window_exceeded`

      - `stop_sequence: String`

        Which custom stop sequence was generated, if any.

        This value will be a non-null string if one of your custom stop sequences was generated.

      - `type: :message`

        Object type.

        For Messages, this is always `"message"`.

        - `:message`

      - `usage: BetaUsage`

        Billing and rate-limit usage.

        Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

        Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

        For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

        Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

          - `ephemeral_1h_input_tokens: Integer`

            The number of input tokens used to create the 1 hour cache entry.

          - `ephemeral_5m_input_tokens: Integer`

            The number of input tokens used to create the 5 minute cache entry.

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `inference_geo: String`

          The geographic region where inference was performed for this request.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `iterations: BetaIterationsUsage`

          Per-iteration token usage breakdown.

          Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

          - Determine which iterations exceeded long context thresholds (>=200k tokens)
          - Calculate the true context window size from the last iteration
          - Understand token accumulation across server-side tool use loops

          - `class BetaMessageIterationUsage`

            Token usage for a sampling iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :message`

              Usage for a sampling iteration

              - `:message`

          - `class BetaCompactionIterationUsage`

            Token usage for a compaction iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :compaction`

              Usage for a compaction iteration

              - `:compaction`

          - `class BetaAdvisorMessageIterationUsage`

            Token usage for an advisor sub-inference iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :advisor_message`

              Usage for an advisor sub-inference iteration

              - `:advisor_message`

          - `class BetaFallbackMessageIterationUsage`

            Token usage for the fallback-model attempt of a server-side fallback request.

            Produced in place of a `message` entry for whichever hop served the
            response. A declined hop produces the existing `message` entry. Whether
            a fallback model served the response is signalled by the presence of this
            entry in `usage.iterations`.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :fallback_message`

              Usage for the fallback-model attempt that served the response

              - `:fallback_message`

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `output_tokens_details: BetaOutputTokensDetails`

          Breakdown of output tokens by category.

          `output_tokens` remains the inclusive, authoritative total used for billing.
          This object provides a read-only decomposition for observability — for example,
          how many of the billed output tokens were spent on internal reasoning that may
          have been summarized before being returned to you.

          - `thinking_tokens: Integer`

            Number of output tokens the model generated as internal reasoning, including
            the thinking-block delimiter tokens.

            Reflects the raw reasoning the model produced, not the (possibly shorter)
            summarized thinking text returned in the response body. Computed by
            re-tokenizing the raw reasoning text, so it may differ from the model's exact
            generation count by a small number of tokens. Always ≤ `output_tokens`;
            `output_tokens - thinking_tokens` approximates the non-reasoning output.

        - `server_tool_use: BetaServerToolUsage`

          The number of server tool requests.

          - `web_fetch_requests: Integer`

            The number of web fetch tool requests.

          - `web_search_requests: Integer`

            The number of web search tool requests.

        - `service_tier: :standard | :priority | :batch`

          If the request used the priority, standard, or batch tier.

          - `:standard`

          - `:priority`

          - `:batch`

        - `speed: :standard | :fast`

          The inference speed mode used for this request.

          - `:standard`

          - `:fast`

    - `type: :message_start`

      - `:message_start`

  - `class BetaRawMessageDeltaEvent`

    - `context_management: BetaContextManagementResponse`

      Information about context management strategies applied during the request

    - `delta: Delta{ container, stop_details, stop_reason, stop_sequence}`

      - `container: BetaContainer`

        Information about the container used in the request (for the code execution tool)

      - `stop_details: BetaRefusalStopDetails`

        Structured information about a refusal.

      - `stop_reason: BetaStopReason`

      - `stop_sequence: String`

    - `type: :message_delta`

      - `:message_delta`

    - `usage: BetaMessageDeltaUsage`

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

      For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

      - `cache_creation_input_tokens: Integer`

        The cumulative number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The cumulative number of input tokens read from the cache.

      - `input_tokens: Integer`

        The cumulative number of input tokens which were used.

      - `iterations: BetaIterationsUsage`

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

        - Determine which iterations exceeded long context thresholds (>=200k tokens)
        - Calculate the true context window size from the last iteration
        - Understand token accumulation across server-side tool use loops

      - `output_tokens: Integer`

        The cumulative number of output tokens which were used.

      - `output_tokens_details: BetaOutputTokensDetails`

        Breakdown of output tokens by category.

        `output_tokens` remains the inclusive, authoritative total used for billing.
        This object provides a read-only decomposition for observability — for example,
        how many of the billed output tokens were spent on internal reasoning that may
        have been summarized before being returned to you.

      - `server_tool_use: BetaServerToolUsage`

        The number of server tool requests.

  - `class BetaRawMessageStopEvent`

    - `type: :message_stop`

      - `:message_stop`

  - `class BetaRawContentBlockStartEvent`

    - `content_block: BetaTextBlock | BetaThinkingBlock | BetaRedactedThinkingBlock | 14 more`

      Response model for a file uploaded to the container.

      - `class BetaTextBlock`

      - `class BetaThinkingBlock`

      - `class BetaRedactedThinkingBlock`

      - `class BetaToolUseBlock`

      - `class BetaServerToolUseBlock`

      - `class BetaWebSearchToolResultBlock`

      - `class BetaWebFetchToolResultBlock`

      - `class BetaAdvisorToolResultBlock`

      - `class BetaCodeExecutionToolResultBlock`

      - `class BetaBashCodeExecutionToolResultBlock`

      - `class BetaTextEditorCodeExecutionToolResultBlock`

      - `class BetaToolSearchToolResultBlock`

      - `class BetaMCPToolUseBlock`

      - `class BetaMCPToolResultBlock`

      - `class BetaContainerUploadBlock`

        Response model for a file uploaded to the container.

      - `class BetaCompactionBlock`

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid
        summary (e.g., malformed output from the model). Clients may round-trip
        compaction blocks with null content; the server treats them as no-ops.

      - `class BetaFallbackBlock`

        Marks the point in `content` where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and
        declined. A turn routed directly by the sticky decision has no such boundary
        and carries no block — the signal for whether a fallback model served the
        response is the presence of a `fallback_message` entry in
        `usage.iterations`, not this block.

        The block is treated like a server-tool content block for streaming: it
        arrives via the standard `content_block_start` / `content_block_stop`
        pair and carries no deltas.

    - `index: Integer`

    - `type: :content_block_start`

      - `:content_block_start`

  - `class BetaRawContentBlockDeltaEvent`

    - `delta: BetaRawContentBlockDelta`

      - `class BetaTextDelta`

        - `text: String`

        - `type: :text_delta`

          - `:text_delta`

      - `class BetaInputJSONDelta`

        - `partial_json: String`

        - `type: :input_json_delta`

          - `:input_json_delta`

      - `class BetaCitationsDelta`

        - `citation: BetaCitationCharLocation | BetaCitationPageLocation | BetaCitationContentBlockLocation | 2 more`

          - `class BetaCitationCharLocation`

          - `class BetaCitationPageLocation`

          - `class BetaCitationContentBlockLocation`

          - `class BetaCitationsWebSearchResultLocation`

          - `class BetaCitationSearchResultLocation`

        - `type: :citations_delta`

          - `:citations_delta`

      - `class BetaThinkingDelta`

        - `estimated_tokens: Integer`

          Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the `thinking-token-count-2026-05-13` beta is set; `null` unless `thinking.display` resolves to `"omitted"` and a count is due this frame. Sum the increments across `thinking_delta` frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; `usage.output_tokens` remains authoritative.

        - `thinking: String`

        - `type: :thinking_delta`

          - `:thinking_delta`

      - `class BetaSignatureDelta`

        - `signature: String`

        - `type: :signature_delta`

          - `:signature_delta`

      - `class BetaCompactionContentBlockDelta`

        - `content: String`

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

        - `type: :compaction_delta`

          - `:compaction_delta`

    - `index: Integer`

    - `type: :content_block_delta`

      - `:content_block_delta`

  - `class BetaRawContentBlockStopEvent`

    - `index: Integer`

    - `type: :content_block_stop`

      - `:content_block_stop`

### Beta Redacted Thinking Block

- `class BetaRedactedThinkingBlock`

  - `data: String`

  - `type: :redacted_thinking`

    - `:redacted_thinking`

### Beta Redacted Thinking Block Param

- `class BetaRedactedThinkingBlockParam`

  - `data: String`

  - `type: :redacted_thinking`

    - `:redacted_thinking`

### Beta Refusal Stop Details

- `class BetaRefusalStopDetails`

  Structured information about a refusal.

  - `category: :cyber | :bio | :reasoning_extraction`

    The policy category that triggered the refusal.

    `null` when the refusal doesn't map to a named category.

    - `:cyber`

    - `:bio`

    - `:reasoning_extraction`

  - `explanation: String`

    Human-readable explanation of the refusal.

    This text is not guaranteed to be stable. `null` when no explanation is available for the category.

  - `fallback_credit_token: String`

    Opaque code that refunds the cache-miss cost when retrying this refused
    request on the fallback model. Pass it as `fallback_credit_token` on the
    retry request. Expires 5 minutes after the refusal.

    The retry is sent either with the same request body (`system`, `messages`,
    `tools`, and other render-shaping fields), or with the same body plus one
    appended `assistant` message whose content is the partial text (with any
    trailing whitespace stripped from the final text block) and paired
    server-tool blocks from this refusal — which also authorizes that
    appended turn as an assistant-prefill continuation on models that otherwise
    disallow prefill. A token minted mid-server-tool-loop whose partial content
    was continuable may only be redeemed the second way — if a same-body retry
    is rejected with a 400 saying the token must be redeemed by continuing the
    partial response, retry the second way instead. Either way: same workspace,
    same platform; a mismatch is a 400. Resending a token for an already-warm
    prefix is permitted but yields no additional credit.

    `null` when the refused model isn't eligible for a fallback credit.

  - `fallback_has_prefill_claim: bool`

    Whether the accompanying `fallback_credit_token` may be redeemed with the
    appended-assistant retry form. Only set when `fallback_credit_token` is
    present.

    `true`: retry by resending the same request body plus one appended
    `assistant` message whose content is this response's `content` with any
    trailing whitespace stripped from the final text block and unpaired
    `tool_use` blocks omitted (the same appended-turn shape described on
    `fallback_credit_token`), with the token attached. `false`: retry by
    resending the original request body unchanged, with the token attached —
    the appended-assistant form is not available for this refusal (no
    continuable partial content, or the request uses `output_format` or a
    `tool_choice` that forces tool use). One exception: when the request used
    `output_format` or a forced `tool_choice` and the refusal arrived after
    server tools (including MCP connector tools) had already executed, the
    token may not be redeemable by either retry form; if the exact-body retry
    is then rejected with a 400 saying the token must be redeemed by
    continuing the partial response, discard the token and retry without it.

    Advisory: if an appended-assistant retry is rejected with a 400 despite
    `true`, fall back to resending the original request body with the token.

  - `recommended_model: String`

    The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

  - `type: :refusal`

    - `:refusal`

### Beta Request Document Block

- `class BetaRequestDocumentBlock`

  - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

    - `class BetaBase64PDFSource`

      - `data: String`

      - `media_type: :"application/pdf"`

        - `:"application/pdf"`

      - `type: :base64`

        - `:base64`

    - `class BetaPlainTextSource`

      - `data: String`

      - `media_type: :"text/plain"`

        - `:"text/plain"`

      - `type: :text`

        - `:text`

    - `class BetaContentBlockSource`

      - `content: String | Array[BetaContentBlockSourceContent]`

        - `String = String`

        - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

          - `class BetaTextBlockParam`

            - `text: String`

            - `type: :text`

              - `:text`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

              - `type: :ephemeral`

                - `:ephemeral`

              - `ttl: :"5m" | :"1h"`

                The time-to-live for the cache control breakpoint.

                This may be one the following values:

                - `5m`: 5 minutes
                - `1h`: 1 hour

                Defaults to `5m`.

                - `:"5m"`

                - `:"1h"`

            - `citations: Array[BetaTextCitationParam]`

              - `class BetaCitationCharLocationParam`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_char_index: Integer`

                - `start_char_index: Integer`

                - `type: :char_location`

                  - `:char_location`

              - `class BetaCitationPageLocationParam`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_page_number: Integer`

                - `start_page_number: Integer`

                - `type: :page_location`

                  - `:page_location`

              - `class BetaCitationContentBlockLocationParam`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `document_index: Integer`

                - `document_title: String`

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `type: :content_block_location`

                  - `:content_block_location`

              - `class BetaCitationWebSearchResultLocationParam`

                - `cited_text: String`

                - `encrypted_index: String`

                - `title: String`

                - `type: :web_search_result_location`

                  - `:web_search_result_location`

                - `url: String`

              - `class BetaCitationSearchResultLocationParam`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `search_result_index: Integer`

                  0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from `document_index`; server-side web search results are not included in this count.

                - `source: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `title: String`

                - `type: :search_result_location`

                  - `:search_result_location`

          - `class BetaImageBlockParam`

            - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

              - `class BetaBase64ImageSource`

                - `data: String`

                - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

                  - `:"image/jpeg"`

                  - `:"image/png"`

                  - `:"image/gif"`

                  - `:"image/webp"`

                - `type: :base64`

                  - `:base64`

              - `class BetaURLImageSource`

                - `type: :url`

                  - `:url`

                - `url: String`

              - `class BetaFileImageSource`

                - `file_id: String`

                - `type: :file`

                  - `:file`

            - `type: :image`

              - `:image`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

      - `type: :content`

        - `:content`

    - `class BetaURLPDFSource`

      - `type: :url`

        - `:url`

      - `url: String`

    - `class BetaFileDocumentSource`

      - `file_id: String`

      - `type: :file`

        - `:file`

  - `type: :document`

    - `:document`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

  - `citations: BetaCitationsConfigParam`

    - `enabled: bool`

  - `context: String`

  - `title: String`

### Beta Request MCP Server Tool Configuration

- `class BetaRequestMCPServerToolConfiguration`

  - `allowed_tools: Array[String]`

  - `enabled: bool`

### Beta Request MCP Server URL Definition

- `class BetaRequestMCPServerURLDefinition`

  - `name: String`

  - `type: :url`

    - `:url`

  - `url: String`

  - `authorization_token: String`

  - `tool_configuration: BetaRequestMCPServerToolConfiguration`

    - `allowed_tools: Array[String]`

    - `enabled: bool`

### Beta Request MCP Tool Result Block Param

- `class BetaRequestMCPToolResultBlockParam`

  - `tool_use_id: String`

  - `type: :mcp_tool_result`

    - `:mcp_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `content: String | Array[BetaTextBlockParam]`

    - `String = String`

    - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

      - `text: String`

      - `type: :text`

        - `:text`

      - `cache_control: BetaCacheControlEphemeral`

        Create a cache control breakpoint at this content block.

      - `citations: Array[BetaTextCitationParam]`

        - `class BetaCitationCharLocationParam`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_char_index: Integer`

          - `start_char_index: Integer`

          - `type: :char_location`

            - `:char_location`

        - `class BetaCitationPageLocationParam`

          - `cited_text: String`

          - `document_index: Integer`

          - `document_title: String`

          - `end_page_number: Integer`

          - `start_page_number: Integer`

          - `type: :page_location`

            - `:page_location`

        - `class BetaCitationContentBlockLocationParam`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `document_index: Integer`

          - `document_title: String`

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `type: :content_block_location`

            - `:content_block_location`

        - `class BetaCitationWebSearchResultLocationParam`

          - `cited_text: String`

          - `encrypted_index: String`

          - `title: String`

          - `type: :web_search_result_location`

            - `:web_search_result_location`

          - `url: String`

        - `class BetaCitationSearchResultLocationParam`

          - `cited_text: String`

            The full text of the cited block range, concatenated.

            Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

          - `end_block_index: Integer`

            Exclusive 0-based end index of the cited block range in the source's `content` array.

            Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

          - `search_result_index: Integer`

            0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

            Counted separately from `document_index`; server-side web search results are not included in this count.

          - `source: String`

          - `start_block_index: Integer`

            0-based index of the first cited block in the source's `content` array.

          - `title: String`

          - `type: :search_result_location`

            - `:search_result_location`

  - `is_error: bool`

### Beta Search Result Block Param

- `class BetaSearchResultBlockParam`

  - `content: Array[BetaTextBlockParam]`

    - `text: String`

    - `type: :text`

      - `:text`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

    - `citations: Array[BetaTextCitationParam]`

      - `class BetaCitationCharLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_char_index: Integer`

        - `start_char_index: Integer`

        - `type: :char_location`

          - `:char_location`

      - `class BetaCitationPageLocationParam`

        - `cited_text: String`

        - `document_index: Integer`

        - `document_title: String`

        - `end_page_number: Integer`

        - `start_page_number: Integer`

        - `type: :page_location`

          - `:page_location`

      - `class BetaCitationContentBlockLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `document_index: Integer`

        - `document_title: String`

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `type: :content_block_location`

          - `:content_block_location`

      - `class BetaCitationWebSearchResultLocationParam`

        - `cited_text: String`

        - `encrypted_index: String`

        - `title: String`

        - `type: :web_search_result_location`

          - `:web_search_result_location`

        - `url: String`

      - `class BetaCitationSearchResultLocationParam`

        - `cited_text: String`

          The full text of the cited block range, concatenated.

          Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

        - `end_block_index: Integer`

          Exclusive 0-based end index of the cited block range in the source's `content` array.

          Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

        - `search_result_index: Integer`

          0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

          Counted separately from `document_index`; server-side web search results are not included in this count.

        - `source: String`

        - `start_block_index: Integer`

          0-based index of the first cited block in the source's `content` array.

        - `title: String`

        - `type: :search_result_location`

          - `:search_result_location`

  - `source: String`

  - `title: String`

  - `type: :search_result`

    - `:search_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

  - `citations: BetaCitationsConfigParam`

    - `enabled: bool`

### Beta Server Tool Caller

- `class BetaServerToolCaller`

  Tool invocation generated by a server-side tool.

  - `tool_id: String`

  - `type: :code_execution_20250825`

    - `:code_execution_20250825`

### Beta Server Tool Caller 20260120

- `class BetaServerToolCaller20260120`

  - `tool_id: String`

  - `type: :code_execution_20260120`

    - `:code_execution_20260120`

### Beta Server Tool Usage

- `class BetaServerToolUsage`

  - `web_fetch_requests: Integer`

    The number of web fetch tool requests.

  - `web_search_requests: Integer`

    The number of web search tool requests.

### Beta Server Tool Use Block

- `class BetaServerToolUseBlock`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: :advisor | :web_search | :web_fetch | 5 more`

    - `:advisor`

    - `:web_search`

    - `:web_fetch`

    - `:code_execution`

    - `:bash_code_execution`

    - `:text_editor_code_execution`

    - `:tool_search_tool_regex`

    - `:tool_search_tool_bm25`

  - `type: :server_tool_use`

    - `:server_tool_use`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Server Tool Use Block Param

- `class BetaServerToolUseBlockParam`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: :advisor | :web_search | :web_fetch | 5 more`

    - `:advisor`

    - `:web_search`

    - `:web_fetch`

    - `:code_execution`

    - `:bash_code_execution`

    - `:text_editor_code_execution`

    - `:tool_search_tool_regex`

    - `:tool_search_tool_bm25`

  - `type: :server_tool_use`

    - `:server_tool_use`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Signature Delta

- `class BetaSignatureDelta`

  - `signature: String`

  - `type: :signature_delta`

    - `:signature_delta`

### Beta Skill

- `class BetaSkill`

  A skill that was loaded in a container (response model).

  - `skill_id: String`

    Skill ID

  - `type: :anthropic | :custom`

    Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

    - `:anthropic`

    - `:custom`

  - `version: String`

    Skill version or 'latest' for most recent version

### Beta Skill Params

- `class BetaSkillParams`

  Specification for a skill to be loaded in a container (request model).

  - `skill_id: String`

    Skill ID

  - `type: :anthropic | :custom`

    Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

    - `:anthropic`

    - `:custom`

  - `version: String`

    Skill version or 'latest' for most recent version

### Beta Stop Reason

- `BetaStopReason = :end_turn | :max_tokens | :stop_sequence | 5 more`

  - `:end_turn`

  - `:max_tokens`

  - `:stop_sequence`

  - `:tool_use`

  - `:pause_turn`

  - `:compaction`

  - `:refusal`

  - `:model_context_window_exceeded`

### Beta Text Block

- `class BetaTextBlock`

  - `citations: Array[BetaTextCitation]`

    Citations supporting the text block.

    The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

    - `class BetaCitationCharLocation`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_char_index: Integer`

      - `file_id: String`

      - `start_char_index: Integer`

      - `type: :char_location`

        - `:char_location`

    - `class BetaCitationPageLocation`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_page_number: Integer`

      - `file_id: String`

      - `start_page_number: Integer`

      - `type: :page_location`

        - `:page_location`

    - `class BetaCitationContentBlockLocation`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `document_index: Integer`

      - `document_title: String`

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `file_id: String`

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `type: :content_block_location`

        - `:content_block_location`

    - `class BetaCitationsWebSearchResultLocation`

      - `cited_text: String`

      - `encrypted_index: String`

      - `title: String`

      - `type: :web_search_result_location`

        - `:web_search_result_location`

      - `url: String`

    - `class BetaCitationSearchResultLocation`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `search_result_index: Integer`

        0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from `document_index`; server-side web search results are not included in this count.

      - `source: String`

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `title: String`

      - `type: :search_result_location`

        - `:search_result_location`

  - `text: String`

  - `type: :text`

    - `:text`

### Beta Text Block Param

- `class BetaTextBlockParam`

  - `text: String`

  - `type: :text`

    - `:text`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `citations: Array[BetaTextCitationParam]`

    - `class BetaCitationCharLocationParam`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_char_index: Integer`

      - `start_char_index: Integer`

      - `type: :char_location`

        - `:char_location`

    - `class BetaCitationPageLocationParam`

      - `cited_text: String`

      - `document_index: Integer`

      - `document_title: String`

      - `end_page_number: Integer`

      - `start_page_number: Integer`

      - `type: :page_location`

        - `:page_location`

    - `class BetaCitationContentBlockLocationParam`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `document_index: Integer`

      - `document_title: String`

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `type: :content_block_location`

        - `:content_block_location`

    - `class BetaCitationWebSearchResultLocationParam`

      - `cited_text: String`

      - `encrypted_index: String`

      - `title: String`

      - `type: :web_search_result_location`

        - `:web_search_result_location`

      - `url: String`

    - `class BetaCitationSearchResultLocationParam`

      - `cited_text: String`

        The full text of the cited block range, concatenated.

        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

      - `end_block_index: Integer`

        Exclusive 0-based end index of the cited block range in the source's `content` array.

        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

      - `search_result_index: Integer`

        0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

        Counted separately from `document_index`; server-side web search results are not included in this count.

      - `source: String`

      - `start_block_index: Integer`

        0-based index of the first cited block in the source's `content` array.

      - `title: String`

      - `type: :search_result_location`

        - `:search_result_location`

### Beta Text Citation

- `BetaTextCitation = BetaCitationCharLocation | BetaCitationPageLocation | BetaCitationContentBlockLocation | 2 more`

  - `class BetaCitationCharLocation`

    - `cited_text: String`

    - `document_index: Integer`

    - `document_title: String`

    - `end_char_index: Integer`

    - `file_id: String`

    - `start_char_index: Integer`

    - `type: :char_location`

      - `:char_location`

  - `class BetaCitationPageLocation`

    - `cited_text: String`

    - `document_index: Integer`

    - `document_title: String`

    - `end_page_number: Integer`

    - `file_id: String`

    - `start_page_number: Integer`

    - `type: :page_location`

      - `:page_location`

  - `class BetaCitationContentBlockLocation`

    - `cited_text: String`

      The full text of the cited block range, concatenated.

      Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    - `document_index: Integer`

    - `document_title: String`

    - `end_block_index: Integer`

      Exclusive 0-based end index of the cited block range in the source's `content` array.

      Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

    - `file_id: String`

    - `start_block_index: Integer`

      0-based index of the first cited block in the source's `content` array.

    - `type: :content_block_location`

      - `:content_block_location`

  - `class BetaCitationsWebSearchResultLocation`

    - `cited_text: String`

    - `encrypted_index: String`

    - `title: String`

    - `type: :web_search_result_location`

      - `:web_search_result_location`

    - `url: String`

  - `class BetaCitationSearchResultLocation`

    - `cited_text: String`

      The full text of the cited block range, concatenated.

      Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    - `end_block_index: Integer`

      Exclusive 0-based end index of the cited block range in the source's `content` array.

      Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

    - `search_result_index: Integer`

      0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

      Counted separately from `document_index`; server-side web search results are not included in this count.

    - `source: String`

    - `start_block_index: Integer`

      0-based index of the first cited block in the source's `content` array.

    - `title: String`

    - `type: :search_result_location`

      - `:search_result_location`

### Beta Text Citation Param

- `BetaTextCitationParam = BetaCitationCharLocationParam | BetaCitationPageLocationParam | BetaCitationContentBlockLocationParam | 2 more`

  - `class BetaCitationCharLocationParam`

    - `cited_text: String`

    - `document_index: Integer`

    - `document_title: String`

    - `end_char_index: Integer`

    - `start_char_index: Integer`

    - `type: :char_location`

      - `:char_location`

  - `class BetaCitationPageLocationParam`

    - `cited_text: String`

    - `document_index: Integer`

    - `document_title: String`

    - `end_page_number: Integer`

    - `start_page_number: Integer`

    - `type: :page_location`

      - `:page_location`

  - `class BetaCitationContentBlockLocationParam`

    - `cited_text: String`

      The full text of the cited block range, concatenated.

      Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    - `document_index: Integer`

    - `document_title: String`

    - `end_block_index: Integer`

      Exclusive 0-based end index of the cited block range in the source's `content` array.

      Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

    - `start_block_index: Integer`

      0-based index of the first cited block in the source's `content` array.

    - `type: :content_block_location`

      - `:content_block_location`

  - `class BetaCitationWebSearchResultLocationParam`

    - `cited_text: String`

    - `encrypted_index: String`

    - `title: String`

    - `type: :web_search_result_location`

      - `:web_search_result_location`

    - `url: String`

  - `class BetaCitationSearchResultLocationParam`

    - `cited_text: String`

      The full text of the cited block range, concatenated.

      Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

    - `end_block_index: Integer`

      Exclusive 0-based end index of the cited block range in the source's `content` array.

      Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

    - `search_result_index: Integer`

      0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

      Counted separately from `document_index`; server-side web search results are not included in this count.

    - `source: String`

    - `start_block_index: Integer`

      0-based index of the first cited block in the source's `content` array.

    - `title: String`

    - `type: :search_result_location`

      - `:search_result_location`

### Beta Text Delta

- `class BetaTextDelta`

  - `text: String`

  - `type: :text_delta`

    - `:text_delta`

### Beta Text Editor Code Execution Create Result Block

- `class BetaTextEditorCodeExecutionCreateResultBlock`

  - `is_file_update: bool`

  - `type: :text_editor_code_execution_create_result`

    - `:text_editor_code_execution_create_result`

### Beta Text Editor Code Execution Create Result Block Param

- `class BetaTextEditorCodeExecutionCreateResultBlockParam`

  - `is_file_update: bool`

  - `type: :text_editor_code_execution_create_result`

    - `:text_editor_code_execution_create_result`

### Beta Text Editor Code Execution Str Replace Result Block

- `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

  - `lines: Array[String]`

  - `new_lines: Integer`

  - `new_start: Integer`

  - `old_lines: Integer`

  - `old_start: Integer`

  - `type: :text_editor_code_execution_str_replace_result`

    - `:text_editor_code_execution_str_replace_result`

### Beta Text Editor Code Execution Str Replace Result Block Param

- `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

  - `type: :text_editor_code_execution_str_replace_result`

    - `:text_editor_code_execution_str_replace_result`

  - `lines: Array[String]`

  - `new_lines: Integer`

  - `new_start: Integer`

  - `old_lines: Integer`

  - `old_start: Integer`

### Beta Text Editor Code Execution Tool Result Block

- `class BetaTextEditorCodeExecutionToolResultBlock`

  - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

    - `class BetaTextEditorCodeExecutionToolResultError`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

        - `:file_not_found`

      - `error_message: String`

      - `type: :text_editor_code_execution_tool_result_error`

        - `:text_editor_code_execution_tool_result_error`

    - `class BetaTextEditorCodeExecutionViewResultBlock`

      - `content: String`

      - `file_type: :text | :image | :pdf`

        - `:text`

        - `:image`

        - `:pdf`

      - `num_lines: Integer`

      - `start_line: Integer`

      - `total_lines: Integer`

      - `type: :text_editor_code_execution_view_result`

        - `:text_editor_code_execution_view_result`

    - `class BetaTextEditorCodeExecutionCreateResultBlock`

      - `is_file_update: bool`

      - `type: :text_editor_code_execution_create_result`

        - `:text_editor_code_execution_create_result`

    - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

      - `lines: Array[String]`

      - `new_lines: Integer`

      - `new_start: Integer`

      - `old_lines: Integer`

      - `old_start: Integer`

      - `type: :text_editor_code_execution_str_replace_result`

        - `:text_editor_code_execution_str_replace_result`

  - `tool_use_id: String`

  - `type: :text_editor_code_execution_tool_result`

    - `:text_editor_code_execution_tool_result`

### Beta Text Editor Code Execution Tool Result Block Param

- `class BetaTextEditorCodeExecutionToolResultBlockParam`

  - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

    - `class BetaTextEditorCodeExecutionToolResultErrorParam`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

        - `:file_not_found`

      - `type: :text_editor_code_execution_tool_result_error`

        - `:text_editor_code_execution_tool_result_error`

      - `error_message: String`

    - `class BetaTextEditorCodeExecutionViewResultBlockParam`

      - `content: String`

      - `file_type: :text | :image | :pdf`

        - `:text`

        - `:image`

        - `:pdf`

      - `type: :text_editor_code_execution_view_result`

        - `:text_editor_code_execution_view_result`

      - `num_lines: Integer`

      - `start_line: Integer`

      - `total_lines: Integer`

    - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

      - `is_file_update: bool`

      - `type: :text_editor_code_execution_create_result`

        - `:text_editor_code_execution_create_result`

    - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

      - `type: :text_editor_code_execution_str_replace_result`

        - `:text_editor_code_execution_str_replace_result`

      - `lines: Array[String]`

      - `new_lines: Integer`

      - `new_start: Integer`

      - `old_lines: Integer`

      - `old_start: Integer`

  - `tool_use_id: String`

  - `type: :text_editor_code_execution_tool_result`

    - `:text_editor_code_execution_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Text Editor Code Execution Tool Result Error

- `class BetaTextEditorCodeExecutionToolResultError`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

    - `:file_not_found`

  - `error_message: String`

  - `type: :text_editor_code_execution_tool_result_error`

    - `:text_editor_code_execution_tool_result_error`

### Beta Text Editor Code Execution Tool Result Error Param

- `class BetaTextEditorCodeExecutionToolResultErrorParam`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

    - `:file_not_found`

  - `type: :text_editor_code_execution_tool_result_error`

    - `:text_editor_code_execution_tool_result_error`

  - `error_message: String`

### Beta Text Editor Code Execution View Result Block

- `class BetaTextEditorCodeExecutionViewResultBlock`

  - `content: String`

  - `file_type: :text | :image | :pdf`

    - `:text`

    - `:image`

    - `:pdf`

  - `num_lines: Integer`

  - `start_line: Integer`

  - `total_lines: Integer`

  - `type: :text_editor_code_execution_view_result`

    - `:text_editor_code_execution_view_result`

### Beta Text Editor Code Execution View Result Block Param

- `class BetaTextEditorCodeExecutionViewResultBlockParam`

  - `content: String`

  - `file_type: :text | :image | :pdf`

    - `:text`

    - `:image`

    - `:pdf`

  - `type: :text_editor_code_execution_view_result`

    - `:text_editor_code_execution_view_result`

  - `num_lines: Integer`

  - `start_line: Integer`

  - `total_lines: Integer`

### Beta Thinking Block

- `class BetaThinkingBlock`

  - `signature: String`

  - `thinking: String`

  - `type: :thinking`

    - `:thinking`

### Beta Thinking Block Param

- `class BetaThinkingBlockParam`

  - `signature: String`

  - `thinking: String`

  - `type: :thinking`

    - `:thinking`

### Beta Thinking Config Adaptive

- `class BetaThinkingConfigAdaptive`

  - `type: :adaptive`

    - `:adaptive`

  - `display_: :summarized | :omitted`

    Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

    - `:summarized`

    - `:omitted`

### Beta Thinking Config Disabled

- `class BetaThinkingConfigDisabled`

  - `type: :disabled`

    - `:disabled`

### Beta Thinking Config Enabled

- `class BetaThinkingConfigEnabled`

  - `budget_tokens: Integer`

    Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

    Must be ≥1024 and less than `max_tokens`.

    See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

  - `type: :enabled`

    - `:enabled`

  - `display_: :summarized | :omitted`

    Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

    - `:summarized`

    - `:omitted`

### Beta Thinking Config Param

- `BetaThinkingConfigParam = BetaThinkingConfigEnabled | BetaThinkingConfigDisabled | BetaThinkingConfigAdaptive`

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include `thinking` content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your `max_tokens` limit.

  See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

  - `class BetaThinkingConfigEnabled`

    - `budget_tokens: Integer`

      Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

      Must be ≥1024 and less than `max_tokens`.

      See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

    - `type: :enabled`

      - `:enabled`

    - `display_: :summarized | :omitted`

      Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

      - `:summarized`

      - `:omitted`

  - `class BetaThinkingConfigDisabled`

    - `type: :disabled`

      - `:disabled`

  - `class BetaThinkingConfigAdaptive`

    - `type: :adaptive`

      - `:adaptive`

    - `display_: :summarized | :omitted`

      Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

      - `:summarized`

      - `:omitted`

### Beta Thinking Delta

- `class BetaThinkingDelta`

  - `estimated_tokens: Integer`

    Per-frame increment of a coarse, running estimate of the tokens this thinking block has produced so far. Present whenever the `thinking-token-count-2026-05-13` beta is set; `null` unless `thinking.display` resolves to `"omitted"` and a count is due this frame. Sum the increments across `thinking_delta` frames on this block for a progress indicator. Each increment is a non-negative multiple of a fixed quantum and the cadence is rate-limited, so this is a deliberately lossy display hint, not a billable count; `usage.output_tokens` remains authoritative.

  - `thinking: String`

  - `type: :thinking_delta`

    - `:thinking_delta`

### Beta Thinking Turns

- `class BetaThinkingTurns`

  - `type: :thinking_turns`

    - `:thinking_turns`

  - `value: Integer`

### Beta Token Task Budget

- `class BetaTokenTaskBudget`

  User-configurable total token budget across contexts.

  - `total: Integer`

    Total token budget across all contexts in the session.

  - `type: :tokens`

    The budget type. Currently only 'tokens' is supported.

    - `:tokens`

  - `remaining: Integer`

    Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

### Beta Tool

- `class BetaTool`

  - `input_schema: InputSchema{ type, properties, required}`

    [JSON schema](https://json-schema.org/draft/2020-12) for this tool's input.

    This defines the shape of the `input` that your tool accepts and that the model will produce.

    - `type: :object`

      - `:object`

    - `properties: Hash[Symbol, untyped]`

    - `required: Array[String]`

  - `name: String`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `description: String`

    Description of what this tool does.

    Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

  - `eager_input_streaming: bool`

    Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

  - `type: :custom`

    - `:custom`

### Beta Tool Bash 20241022

- `class BetaToolBash20241022`

  - `name: :bash`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:bash`

  - `type: :bash_20241022`

    - `:bash_20241022`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Bash 20250124

- `class BetaToolBash20250124`

  - `name: :bash`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:bash`

  - `type: :bash_20250124`

    - `:bash_20250124`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Choice

- `BetaToolChoice = BetaToolChoiceAuto | BetaToolChoiceAny | BetaToolChoiceTool | BetaToolChoiceNone`

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

  - `class BetaToolChoiceAuto`

    The model will automatically decide whether to use tools.

    - `type: :auto`

      - `:auto`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output at most one tool use.

  - `class BetaToolChoiceAny`

    The model will use any available tools.

    - `type: :any`

      - `:any`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceTool`

    The model will use the specified tool with `tool_choice.name`.

    - `name: String`

      The name of the tool to use.

    - `type: :tool`

      - `:tool`

    - `disable_parallel_tool_use: bool`

      Whether to disable parallel tool use.

      Defaults to `false`. If set to `true`, the model will output exactly one tool use.

  - `class BetaToolChoiceNone`

    The model will not be allowed to use tools.

    - `type: :none`

      - `:none`

### Beta Tool Choice Any

- `class BetaToolChoiceAny`

  The model will use any available tools.

  - `type: :any`

    - `:any`

  - `disable_parallel_tool_use: bool`

    Whether to disable parallel tool use.

    Defaults to `false`. If set to `true`, the model will output exactly one tool use.

### Beta Tool Choice Auto

- `class BetaToolChoiceAuto`

  The model will automatically decide whether to use tools.

  - `type: :auto`

    - `:auto`

  - `disable_parallel_tool_use: bool`

    Whether to disable parallel tool use.

    Defaults to `false`. If set to `true`, the model will output at most one tool use.

### Beta Tool Choice None

- `class BetaToolChoiceNone`

  The model will not be allowed to use tools.

  - `type: :none`

    - `:none`

### Beta Tool Choice Tool

- `class BetaToolChoiceTool`

  The model will use the specified tool with `tool_choice.name`.

  - `name: String`

    The name of the tool to use.

  - `type: :tool`

    - `:tool`

  - `disable_parallel_tool_use: bool`

    Whether to disable parallel tool use.

    Defaults to `false`. If set to `true`, the model will output exactly one tool use.

### Beta Tool Computer Use 20241022

- `class BetaToolComputerUse20241022`

  - `display_height_px: Integer`

    The height of the display in pixels.

  - `display_width_px: Integer`

    The width of the display in pixels.

  - `name: :computer`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:computer`

  - `type: :computer_20241022`

    - `:computer_20241022`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `display_number: Integer`

    The X11 display number (e.g. 0, 1) for the display.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Computer Use 20250124

- `class BetaToolComputerUse20250124`

  - `display_height_px: Integer`

    The height of the display in pixels.

  - `display_width_px: Integer`

    The width of the display in pixels.

  - `name: :computer`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:computer`

  - `type: :computer_20250124`

    - `:computer_20250124`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `display_number: Integer`

    The X11 display number (e.g. 0, 1) for the display.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Computer Use 20251124

- `class BetaToolComputerUse20251124`

  - `display_height_px: Integer`

    The height of the display in pixels.

  - `display_width_px: Integer`

    The width of the display in pixels.

  - `name: :computer`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:computer`

  - `type: :computer_20251124`

    - `:computer_20251124`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `display_number: Integer`

    The X11 display number (e.g. 0, 1) for the display.

  - `enable_zoom: bool`

    Whether to enable an action to take a zoomed-in screenshot of the screen.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Reference Block

- `class BetaToolReferenceBlock`

  - `tool_name: String`

  - `type: :tool_reference`

    - `:tool_reference`

### Beta Tool Reference Block Param

- `class BetaToolReferenceBlockParam`

  Tool reference block that can be included in tool_result content.

  - `tool_name: String`

  - `type: :tool_reference`

    - `:tool_reference`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

### Beta Tool Result Block Param

- `class BetaToolResultBlockParam`

  - `tool_use_id: String`

  - `type: :tool_result`

    - `:tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

    - `String = String`

    - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

      - `class BetaTextBlockParam`

        - `text: String`

        - `type: :text`

          - `:text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: Array[BetaTextCitationParam]`

          - `class BetaCitationCharLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocationParam`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationWebSearchResultLocationParam`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocationParam`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

      - `class BetaImageBlockParam`

        - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

          - `class BetaBase64ImageSource`

            - `data: String`

            - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

              - `:"image/jpeg"`

              - `:"image/png"`

              - `:"image/gif"`

              - `:"image/webp"`

            - `type: :base64`

              - `:base64`

          - `class BetaURLImageSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileImageSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :image`

          - `:image`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

      - `class BetaSearchResultBlockParam`

        - `content: Array[BetaTextBlockParam]`

          - `text: String`

          - `type: :text`

          - `cache_control: BetaCacheControlEphemeral`

            Create a cache control breakpoint at this content block.

          - `citations: Array[BetaTextCitationParam]`

        - `source: String`

        - `title: String`

        - `type: :search_result`

          - `:search_result`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          - `enabled: bool`

      - `class BetaRequestDocumentBlock`

        - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

          - `class BetaContentBlockSource`

            - `content: String | Array[BetaContentBlockSourceContent]`

              - `String = String`

              - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                - `class BetaTextBlockParam`

                - `class BetaImageBlockParam`

            - `type: :content`

              - `:content`

          - `class BetaURLPDFSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileDocumentSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :document`

          - `:document`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

        - `context: String`

        - `title: String`

      - `class BetaToolReferenceBlockParam`

        Tool reference block that can be included in tool_result content.

        - `tool_name: String`

        - `type: :tool_reference`

          - `:tool_reference`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

  - `is_error: bool`

### Beta Tool Search Tool Bm25 20251119

- `class BetaToolSearchToolBm25_20251119`

  - `name: :tool_search_tool_bm25`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:tool_search_tool_bm25`

  - `type: :tool_search_tool_bm25_20251119 | :tool_search_tool_bm25`

    - `:tool_search_tool_bm25_20251119`

    - `:tool_search_tool_bm25`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Search Tool Regex 20251119

- `class BetaToolSearchToolRegex20251119`

  - `name: :tool_search_tool_regex`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:tool_search_tool_regex`

  - `type: :tool_search_tool_regex_20251119 | :tool_search_tool_regex`

    - `:tool_search_tool_regex_20251119`

    - `:tool_search_tool_regex`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Search Tool Result Block

- `class BetaToolSearchToolResultBlock`

  - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

    - `class BetaToolSearchToolResultError`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

      - `error_message: String`

      - `type: :tool_search_tool_result_error`

        - `:tool_search_tool_result_error`

    - `class BetaToolSearchToolSearchResultBlock`

      - `tool_references: Array[BetaToolReferenceBlock]`

        - `tool_name: String`

        - `type: :tool_reference`

          - `:tool_reference`

      - `type: :tool_search_tool_search_result`

        - `:tool_search_tool_search_result`

  - `tool_use_id: String`

  - `type: :tool_search_tool_result`

    - `:tool_search_tool_result`

### Beta Tool Search Tool Result Block Param

- `class BetaToolSearchToolResultBlockParam`

  - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

    - `class BetaToolSearchToolResultErrorParam`

      - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:too_many_requests`

        - `:execution_time_exceeded`

      - `type: :tool_search_tool_result_error`

        - `:tool_search_tool_result_error`

      - `error_message: String`

    - `class BetaToolSearchToolSearchResultBlockParam`

      - `tool_references: Array[BetaToolReferenceBlockParam]`

        - `tool_name: String`

        - `type: :tool_reference`

          - `:tool_reference`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

          - `type: :ephemeral`

            - `:ephemeral`

          - `ttl: :"5m" | :"1h"`

            The time-to-live for the cache control breakpoint.

            This may be one the following values:

            - `5m`: 5 minutes
            - `1h`: 1 hour

            Defaults to `5m`.

            - `:"5m"`

            - `:"1h"`

      - `type: :tool_search_tool_search_result`

        - `:tool_search_tool_search_result`

  - `tool_use_id: String`

  - `type: :tool_search_tool_result`

    - `:tool_search_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

### Beta Tool Search Tool Result Error

- `class BetaToolSearchToolResultError`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

  - `error_message: String`

  - `type: :tool_search_tool_result_error`

    - `:tool_search_tool_result_error`

### Beta Tool Search Tool Result Error Param

- `class BetaToolSearchToolResultErrorParam`

  - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:too_many_requests`

    - `:execution_time_exceeded`

  - `type: :tool_search_tool_result_error`

    - `:tool_search_tool_result_error`

  - `error_message: String`

### Beta Tool Search Tool Search Result Block

- `class BetaToolSearchToolSearchResultBlock`

  - `tool_references: Array[BetaToolReferenceBlock]`

    - `tool_name: String`

    - `type: :tool_reference`

      - `:tool_reference`

  - `type: :tool_search_tool_search_result`

    - `:tool_search_tool_search_result`

### Beta Tool Search Tool Search Result Block Param

- `class BetaToolSearchToolSearchResultBlockParam`

  - `tool_references: Array[BetaToolReferenceBlockParam]`

    - `tool_name: String`

    - `type: :tool_reference`

      - `:tool_reference`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

  - `type: :tool_search_tool_search_result`

    - `:tool_search_tool_search_result`

### Beta Tool Text Editor 20241022

- `class BetaToolTextEditor20241022`

  - `name: :str_replace_editor`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:str_replace_editor`

  - `type: :text_editor_20241022`

    - `:text_editor_20241022`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Text Editor 20250124

- `class BetaToolTextEditor20250124`

  - `name: :str_replace_editor`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:str_replace_editor`

  - `type: :text_editor_20250124`

    - `:text_editor_20250124`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Text Editor 20250429

- `class BetaToolTextEditor20250429`

  - `name: :str_replace_based_edit_tool`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:str_replace_based_edit_tool`

  - `type: :text_editor_20250429`

    - `:text_editor_20250429`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Text Editor 20250728

- `class BetaToolTextEditor20250728`

  - `name: :str_replace_based_edit_tool`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:str_replace_based_edit_tool`

  - `type: :text_editor_20250728`

    - `:text_editor_20250728`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `input_examples: Array[Hash[Symbol, untyped]]`

  - `max_characters: Integer`

    Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Tool Union

- `BetaToolUnion = BetaTool | BetaToolBash20241022 | BetaToolBash20250124 | 20 more`

  Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

  - `class BetaTool`

    - `input_schema: InputSchema{ type, properties, required}`

      [JSON schema](https://json-schema.org/draft/2020-12) for this tool's input.

      This defines the shape of the `input` that your tool accepts and that the model will produce.

      - `type: :object`

        - `:object`

      - `properties: Hash[Symbol, untyped]`

      - `required: Array[String]`

    - `name: String`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

      - `type: :ephemeral`

        - `:ephemeral`

      - `ttl: :"5m" | :"1h"`

        The time-to-live for the cache control breakpoint.

        This may be one the following values:

        - `5m`: 5 minutes
        - `1h`: 1 hour

        Defaults to `5m`.

        - `:"5m"`

        - `:"1h"`

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `description: String`

      Description of what this tool does.

      Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

    - `eager_input_streaming: bool`

      Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `type: :custom`

      - `:custom`

  - `class BetaToolBash20241022`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20241022`

      - `:bash_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolBash20250124`

    - `name: :bash`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:bash`

    - `type: :bash_20250124`

      - `:bash_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250522`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250522`

      - `:code_execution_20250522`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20250825`

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20250825`

      - `:code_execution_20250825`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaCodeExecutionTool20260120`

    Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

    - `name: :code_execution`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:code_execution`

    - `type: :code_execution_20260120`

      - `:code_execution_20260120`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20241022`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20241022`

      - `:computer_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMemoryTool20250818`

    - `name: :memory`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:memory`

    - `type: :memory_20250818`

      - `:memory_20250818`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20250124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20250124`

      - `:computer_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20241022`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20241022`

      - `:text_editor_20241022`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolComputerUse20251124`

    - `display_height_px: Integer`

      The height of the display in pixels.

    - `display_width_px: Integer`

      The width of the display in pixels.

    - `name: :computer`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:computer`

    - `type: :computer_20251124`

      - `:computer_20251124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `display_number: Integer`

      The X11 display number (e.g. 0, 1) for the display.

    - `enable_zoom: bool`

      Whether to enable an action to take a zoomed-in screenshot of the screen.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250124`

    - `name: :str_replace_editor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_editor`

    - `type: :text_editor_20250124`

      - `:text_editor_20250124`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250429`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250429`

      - `:text_editor_20250429`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolTextEditor20250728`

    - `name: :str_replace_based_edit_tool`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:str_replace_based_edit_tool`

    - `type: :text_editor_20250728`

      - `:text_editor_20250728`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `input_examples: Array[Hash[Symbol, untyped]]`

    - `max_characters: Integer`

      Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20250305`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20250305`

      - `:web_search_20250305`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

      - `type: :approximate`

        - `:approximate`

      - `city: String`

        The city of the user.

      - `country: String`

        The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

      - `region: String`

        The region of the user.

      - `timezone: String`

        The [IANA timezone](https://nodatime.org/TimeZones) of the user.

  - `class BetaWebFetchTool20250910`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20250910`

      - `:web_fetch_20250910`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

      - `enabled: bool`

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebSearchTool20260209`

    - `name: :web_search`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_search`

    - `type: :web_search_20260209`

      - `:web_search_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

    - `blocked_domains: Array[String]`

      If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `user_location: BetaUserLocation`

      Parameters for the user's location. Used to provide more relevant search results.

  - `class BetaWebFetchTool20260209`

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260209`

      - `:web_fetch_20260209`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaWebFetchTool20260309`

    Web fetch tool with use_cache parameter for bypassing cached content.

    - `name: :web_fetch`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:web_fetch`

    - `type: :web_fetch_20260309`

      - `:web_fetch_20260309`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `allowed_domains: Array[String]`

      List of domains to allow fetching from

    - `blocked_domains: Array[String]`

      List of domains to block fetching from

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      Citations configuration for fetched documents. Citations are disabled by default.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_content_tokens: Integer`

      Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

    - `use_cache: bool`

      Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

  - `class BetaAdvisorTool20260301`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `:"claude-fable-5"`

          Next generation of intelligence for the hardest knowledge work and coding problems

        - `:"claude-mythos-5"`

          Most capable model for cybersecurity and biology research

        - `:"claude-opus-4-8"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-opus-4-7"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-mythos-preview"`

          New class of intelligence, strongest in coding and cybersecurity

        - `:"claude-opus-4-6"`

          Frontier intelligence for long-running agents and coding

        - `:"claude-sonnet-4-6"`

          Best combination of speed and intelligence

        - `:"claude-haiku-4-5"`

          Fastest model with near-frontier intelligence

        - `:"claude-haiku-4-5-20251001"`

          Fastest model with near-frontier intelligence

        - `:"claude-opus-4-5"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-opus-4-5-20251101"`

          Premium model combining maximum intelligence with practical performance

        - `:"claude-sonnet-4-5"`

          High-performance model for agents and coding

        - `:"claude-sonnet-4-5-20250929"`

          High-performance model for agents and coding

        - `:"claude-opus-4-1"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-1-20250805"`

          Exceptional model for specialized complex tasks

        - `:"claude-opus-4-0"`

          Powerful model for complex tasks

        - `:"claude-opus-4-20250514"`

          Powerful model for complex tasks

        - `:"claude-sonnet-4-0"`

          High-performance model with extended thinking

        - `:"claude-sonnet-4-20250514"`

          High-performance model with extended thinking

        - `:"claude-3-haiku-20240307"`

          Fast and cost-effective model

      - `String = String`

    - `name: :advisor`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:advisor`

    - `type: :advisor_20260301`

      - `:advisor_20260301`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `caching: BetaCacheControlEphemeral`

      Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `max_tokens: Integer`

      Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

    - `max_uses: Integer`

      Maximum number of times the tool can be used in the API request.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolBm25_20251119`

    - `name: :tool_search_tool_bm25`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_bm25`

    - `type: :tool_search_tool_bm25_20251119 | :tool_search_tool_bm25`

      - `:tool_search_tool_bm25_20251119`

      - `:tool_search_tool_bm25`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaToolSearchToolRegex20251119`

    - `name: :tool_search_tool_regex`

      Name of the tool.

      This is how the tool will be called by the model and in `tool_use` blocks.

      - `:tool_search_tool_regex`

    - `type: :tool_search_tool_regex_20251119 | :tool_search_tool_regex`

      - `:tool_search_tool_regex_20251119`

      - `:tool_search_tool_regex`

    - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

      - `:direct`

      - `:code_execution_20250825`

      - `:code_execution_20260120`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `defer_loading: bool`

      If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

    - `strict: bool`

      When true, guarantees schema validation on tool names and inputs

  - `class BetaMCPToolset`

    Configuration for a group of tools from an MCP server.

    Allows configuring enabled status and defer_loading for all tools
    from an MCP server, with optional per-tool overrides.

    - `mcp_server_name: String`

      Name of the MCP server to configure tools for

    - `type: :mcp_toolset`

      - `:mcp_toolset`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `configs: Hash[Symbol, BetaMCPToolConfig]`

      Configuration overrides for specific tools, keyed by tool name

      - `defer_loading: bool`

      - `enabled: bool`

    - `default_config: BetaMCPToolDefaultConfig`

      Default configuration applied to all tools from this server

      - `defer_loading: bool`

      - `enabled: bool`

### Beta Tool Use Block

- `class BetaToolUseBlock`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: String`

  - `type: :tool_use`

    - `:tool_use`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Tool Use Block Param

- `class BetaToolUseBlockParam`

  - `id: String`

  - `input: Hash[Symbol, untyped]`

  - `name: String`

  - `type: :tool_use`

    - `:tool_use`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Tool Uses Keep

- `class BetaToolUsesKeep`

  - `type: :tool_uses`

    - `:tool_uses`

  - `value: Integer`

### Beta Tool Uses Trigger

- `class BetaToolUsesTrigger`

  - `type: :tool_uses`

    - `:tool_uses`

  - `value: Integer`

### Beta URL Image Source

- `class BetaURLImageSource`

  - `type: :url`

    - `:url`

  - `url: String`

### Beta URL PDF Source

- `class BetaURLPDFSource`

  - `type: :url`

    - `:url`

  - `url: String`

### Beta Usage

- `class BetaUsage`

  - `cache_creation: BetaCacheCreation`

    Breakdown of cached tokens by TTL

    - `ephemeral_1h_input_tokens: Integer`

      The number of input tokens used to create the 1 hour cache entry.

    - `ephemeral_5m_input_tokens: Integer`

      The number of input tokens used to create the 5 minute cache entry.

  - `cache_creation_input_tokens: Integer`

    The number of input tokens used to create the cache entry.

  - `cache_read_input_tokens: Integer`

    The number of input tokens read from the cache.

  - `inference_geo: String`

    The geographic region where inference was performed for this request.

  - `input_tokens: Integer`

    The number of input tokens which were used.

  - `iterations: BetaIterationsUsage`

    Per-iteration token usage breakdown.

    Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

    - Determine which iterations exceeded long context thresholds (>=200k tokens)
    - Calculate the true context window size from the last iteration
    - Understand token accumulation across server-side tool use loops

    - `class BetaMessageIterationUsage`

      Token usage for a sampling iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `:"claude-fable-5"`

            Next generation of intelligence for the hardest knowledge work and coding problems

          - `:"claude-mythos-5"`

            Most capable model for cybersecurity and biology research

          - `:"claude-opus-4-8"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-opus-4-7"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-mythos-preview"`

            New class of intelligence, strongest in coding and cybersecurity

          - `:"claude-opus-4-6"`

            Frontier intelligence for long-running agents and coding

          - `:"claude-sonnet-4-6"`

            Best combination of speed and intelligence

          - `:"claude-haiku-4-5"`

            Fastest model with near-frontier intelligence

          - `:"claude-haiku-4-5-20251001"`

            Fastest model with near-frontier intelligence

          - `:"claude-opus-4-5"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-opus-4-5-20251101"`

            Premium model combining maximum intelligence with practical performance

          - `:"claude-sonnet-4-5"`

            High-performance model for agents and coding

          - `:"claude-sonnet-4-5-20250929"`

            High-performance model for agents and coding

          - `:"claude-opus-4-1"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-1-20250805"`

            Exceptional model for specialized complex tasks

          - `:"claude-opus-4-0"`

            Powerful model for complex tasks

          - `:"claude-opus-4-20250514"`

            Powerful model for complex tasks

          - `:"claude-sonnet-4-0"`

            High-performance model with extended thinking

          - `:"claude-sonnet-4-20250514"`

            High-performance model with extended thinking

          - `:"claude-3-haiku-20240307"`

            Fast and cost-effective model

        - `String = String`

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :message`

        Usage for a sampling iteration

        - `:message`

    - `class BetaCompactionIterationUsage`

      Token usage for a compaction iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :compaction`

        Usage for a compaction iteration

        - `:compaction`

    - `class BetaAdvisorMessageIterationUsage`

      Token usage for an advisor sub-inference iteration.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :advisor_message`

        Usage for an advisor sub-inference iteration

        - `:advisor_message`

    - `class BetaFallbackMessageIterationUsage`

      Token usage for the fallback-model attempt of a server-side fallback request.

      Produced in place of a `message` entry for whichever hop served the
      response. A declined hop produces the existing `message` entry. Whether
      a fallback model served the response is signalled by the presence of this
      entry in `usage.iterations`.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `type: :fallback_message`

        Usage for the fallback-model attempt that served the response

        - `:fallback_message`

  - `output_tokens: Integer`

    The number of output tokens which were used.

  - `output_tokens_details: BetaOutputTokensDetails`

    Breakdown of output tokens by category.

    `output_tokens` remains the inclusive, authoritative total used for billing.
    This object provides a read-only decomposition for observability — for example,
    how many of the billed output tokens were spent on internal reasoning that may
    have been summarized before being returned to you.

    - `thinking_tokens: Integer`

      Number of output tokens the model generated as internal reasoning, including
      the thinking-block delimiter tokens.

      Reflects the raw reasoning the model produced, not the (possibly shorter)
      summarized thinking text returned in the response body. Computed by
      re-tokenizing the raw reasoning text, so it may differ from the model's exact
      generation count by a small number of tokens. Always ≤ `output_tokens`;
      `output_tokens - thinking_tokens` approximates the non-reasoning output.

  - `server_tool_use: BetaServerToolUsage`

    The number of server tool requests.

    - `web_fetch_requests: Integer`

      The number of web fetch tool requests.

    - `web_search_requests: Integer`

      The number of web search tool requests.

  - `service_tier: :standard | :priority | :batch`

    If the request used the priority, standard, or batch tier.

    - `:standard`

    - `:priority`

    - `:batch`

  - `speed: :standard | :fast`

    The inference speed mode used for this request.

    - `:standard`

    - `:fast`

### Beta User Location

- `class BetaUserLocation`

  - `type: :approximate`

    - `:approximate`

  - `city: String`

    The city of the user.

  - `country: String`

    The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

  - `region: String`

    The region of the user.

  - `timezone: String`

    The [IANA timezone](https://nodatime.org/TimeZones) of the user.

### Beta Web Fetch Block

- `class BetaWebFetchBlock`

  - `content: BetaDocumentBlock`

    - `citations: BetaCitationConfig`

      Citation configuration for the document

      - `enabled: bool`

    - `source: BetaBase64PDFSource | BetaPlainTextSource`

      - `class BetaBase64PDFSource`

        - `data: String`

        - `media_type: :"application/pdf"`

          - `:"application/pdf"`

        - `type: :base64`

          - `:base64`

      - `class BetaPlainTextSource`

        - `data: String`

        - `media_type: :"text/plain"`

          - `:"text/plain"`

        - `type: :text`

          - `:text`

    - `title: String`

      The title of the document

    - `type: :document`

      - `:document`

  - `retrieved_at: String`

    ISO 8601 timestamp when the content was retrieved

  - `type: :web_fetch_result`

    - `:web_fetch_result`

  - `url: String`

    Fetched content URL

### Beta Web Fetch Block Param

- `class BetaWebFetchBlockParam`

  - `content: BetaRequestDocumentBlock`

    - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

      - `class BetaBase64PDFSource`

        - `data: String`

        - `media_type: :"application/pdf"`

          - `:"application/pdf"`

        - `type: :base64`

          - `:base64`

      - `class BetaPlainTextSource`

        - `data: String`

        - `media_type: :"text/plain"`

          - `:"text/plain"`

        - `type: :text`

          - `:text`

      - `class BetaContentBlockSource`

        - `content: String | Array[BetaContentBlockSourceContent]`

          - `String = String`

          - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

            - `class BetaTextBlockParam`

              - `text: String`

              - `type: :text`

                - `:text`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

                - `type: :ephemeral`

                  - `:ephemeral`

                - `ttl: :"5m" | :"1h"`

                  The time-to-live for the cache control breakpoint.

                  This may be one the following values:

                  - `5m`: 5 minutes
                  - `1h`: 1 hour

                  Defaults to `5m`.

                  - `:"5m"`

                  - `:"1h"`

              - `citations: Array[BetaTextCitationParam]`

                - `class BetaCitationCharLocationParam`

                  - `cited_text: String`

                  - `document_index: Integer`

                  - `document_title: String`

                  - `end_char_index: Integer`

                  - `start_char_index: Integer`

                  - `type: :char_location`

                    - `:char_location`

                - `class BetaCitationPageLocationParam`

                  - `cited_text: String`

                  - `document_index: Integer`

                  - `document_title: String`

                  - `end_page_number: Integer`

                  - `start_page_number: Integer`

                  - `type: :page_location`

                    - `:page_location`

                - `class BetaCitationContentBlockLocationParam`

                  - `cited_text: String`

                    The full text of the cited block range, concatenated.

                    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                  - `document_index: Integer`

                  - `document_title: String`

                  - `end_block_index: Integer`

                    Exclusive 0-based end index of the cited block range in the source's `content` array.

                    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                  - `start_block_index: Integer`

                    0-based index of the first cited block in the source's `content` array.

                  - `type: :content_block_location`

                    - `:content_block_location`

                - `class BetaCitationWebSearchResultLocationParam`

                  - `cited_text: String`

                  - `encrypted_index: String`

                  - `title: String`

                  - `type: :web_search_result_location`

                    - `:web_search_result_location`

                  - `url: String`

                - `class BetaCitationSearchResultLocationParam`

                  - `cited_text: String`

                    The full text of the cited block range, concatenated.

                    Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                  - `end_block_index: Integer`

                    Exclusive 0-based end index of the cited block range in the source's `content` array.

                    Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                  - `search_result_index: Integer`

                    0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                    Counted separately from `document_index`; server-side web search results are not included in this count.

                  - `source: String`

                  - `start_block_index: Integer`

                    0-based index of the first cited block in the source's `content` array.

                  - `title: String`

                  - `type: :search_result_location`

                    - `:search_result_location`

            - `class BetaImageBlockParam`

              - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

                - `class BetaBase64ImageSource`

                  - `data: String`

                  - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

                    - `:"image/jpeg"`

                    - `:"image/png"`

                    - `:"image/gif"`

                    - `:"image/webp"`

                  - `type: :base64`

                    - `:base64`

                - `class BetaURLImageSource`

                  - `type: :url`

                    - `:url`

                  - `url: String`

                - `class BetaFileImageSource`

                  - `file_id: String`

                  - `type: :file`

                    - `:file`

              - `type: :image`

                - `:image`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

        - `type: :content`

          - `:content`

      - `class BetaURLPDFSource`

        - `type: :url`

          - `:url`

        - `url: String`

      - `class BetaFileDocumentSource`

        - `file_id: String`

        - `type: :file`

          - `:file`

    - `type: :document`

      - `:document`

    - `cache_control: BetaCacheControlEphemeral`

      Create a cache control breakpoint at this content block.

    - `citations: BetaCitationsConfigParam`

      - `enabled: bool`

    - `context: String`

    - `title: String`

  - `type: :web_fetch_result`

    - `:web_fetch_result`

  - `url: String`

    Fetched content URL

  - `retrieved_at: String`

    ISO 8601 timestamp when the content was retrieved

### Beta Web Fetch Tool 20250910

- `class BetaWebFetchTool20250910`

  - `name: :web_fetch`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:web_fetch`

  - `type: :web_fetch_20250910`

    - `:web_fetch_20250910`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `allowed_domains: Array[String]`

    List of domains to allow fetching from

  - `blocked_domains: Array[String]`

    List of domains to block fetching from

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `citations: BetaCitationsConfigParam`

    Citations configuration for fetched documents. Citations are disabled by default.

    - `enabled: bool`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_content_tokens: Integer`

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Web Fetch Tool 20260209

- `class BetaWebFetchTool20260209`

  - `name: :web_fetch`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:web_fetch`

  - `type: :web_fetch_20260209`

    - `:web_fetch_20260209`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `allowed_domains: Array[String]`

    List of domains to allow fetching from

  - `blocked_domains: Array[String]`

    List of domains to block fetching from

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `citations: BetaCitationsConfigParam`

    Citations configuration for fetched documents. Citations are disabled by default.

    - `enabled: bool`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_content_tokens: Integer`

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

### Beta Web Fetch Tool 20260309

- `class BetaWebFetchTool20260309`

  Web fetch tool with use_cache parameter for bypassing cached content.

  - `name: :web_fetch`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:web_fetch`

  - `type: :web_fetch_20260309`

    - `:web_fetch_20260309`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `allowed_domains: Array[String]`

    List of domains to allow fetching from

  - `blocked_domains: Array[String]`

    List of domains to block fetching from

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `citations: BetaCitationsConfigParam`

    Citations configuration for fetched documents. Citations are disabled by default.

    - `enabled: bool`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_content_tokens: Integer`

    Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

  - `use_cache: bool`

    Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

### Beta Web Fetch Tool Result Block

- `class BetaWebFetchToolResultBlock`

  - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

    - `class BetaWebFetchToolResultErrorBlock`

      - `error_code: BetaWebFetchToolResultErrorCode`

        - `:invalid_tool_input`

        - `:url_too_long`

        - `:url_not_allowed`

        - `:url_not_in_prior_context`

        - `:url_not_accessible`

        - `:unsupported_content_type`

        - `:too_many_requests`

        - `:max_uses_exceeded`

        - `:unavailable`

      - `type: :web_fetch_tool_result_error`

        - `:web_fetch_tool_result_error`

    - `class BetaWebFetchBlock`

      - `content: BetaDocumentBlock`

        - `citations: BetaCitationConfig`

          Citation configuration for the document

          - `enabled: bool`

        - `source: BetaBase64PDFSource | BetaPlainTextSource`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

        - `title: String`

          The title of the document

        - `type: :document`

          - `:document`

      - `retrieved_at: String`

        ISO 8601 timestamp when the content was retrieved

      - `type: :web_fetch_result`

        - `:web_fetch_result`

      - `url: String`

        Fetched content URL

  - `tool_use_id: String`

  - `type: :web_fetch_tool_result`

    - `:web_fetch_tool_result`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Web Fetch Tool Result Block Param

- `class BetaWebFetchToolResultBlockParam`

  - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

    - `class BetaWebFetchToolResultErrorBlockParam`

      - `error_code: BetaWebFetchToolResultErrorCode`

        - `:invalid_tool_input`

        - `:url_too_long`

        - `:url_not_allowed`

        - `:url_not_in_prior_context`

        - `:url_not_accessible`

        - `:unsupported_content_type`

        - `:too_many_requests`

        - `:max_uses_exceeded`

        - `:unavailable`

      - `type: :web_fetch_tool_result_error`

        - `:web_fetch_tool_result_error`

    - `class BetaWebFetchBlockParam`

      - `content: BetaRequestDocumentBlock`

        - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

          - `class BetaBase64PDFSource`

            - `data: String`

            - `media_type: :"application/pdf"`

              - `:"application/pdf"`

            - `type: :base64`

              - `:base64`

          - `class BetaPlainTextSource`

            - `data: String`

            - `media_type: :"text/plain"`

              - `:"text/plain"`

            - `type: :text`

              - `:text`

          - `class BetaContentBlockSource`

            - `content: String | Array[BetaContentBlockSourceContent]`

              - `String = String`

              - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                - `class BetaTextBlockParam`

                  - `text: String`

                  - `type: :text`

                    - `:text`

                  - `cache_control: BetaCacheControlEphemeral`

                    Create a cache control breakpoint at this content block.

                    - `type: :ephemeral`

                      - `:ephemeral`

                    - `ttl: :"5m" | :"1h"`

                      The time-to-live for the cache control breakpoint.

                      This may be one the following values:

                      - `5m`: 5 minutes
                      - `1h`: 1 hour

                      Defaults to `5m`.

                      - `:"5m"`

                      - `:"1h"`

                  - `citations: Array[BetaTextCitationParam]`

                    - `class BetaCitationCharLocationParam`

                      - `cited_text: String`

                      - `document_index: Integer`

                      - `document_title: String`

                      - `end_char_index: Integer`

                      - `start_char_index: Integer`

                      - `type: :char_location`

                        - `:char_location`

                    - `class BetaCitationPageLocationParam`

                      - `cited_text: String`

                      - `document_index: Integer`

                      - `document_title: String`

                      - `end_page_number: Integer`

                      - `start_page_number: Integer`

                      - `type: :page_location`

                        - `:page_location`

                    - `class BetaCitationContentBlockLocationParam`

                      - `cited_text: String`

                        The full text of the cited block range, concatenated.

                        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                      - `document_index: Integer`

                      - `document_title: String`

                      - `end_block_index: Integer`

                        Exclusive 0-based end index of the cited block range in the source's `content` array.

                        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                      - `start_block_index: Integer`

                        0-based index of the first cited block in the source's `content` array.

                      - `type: :content_block_location`

                        - `:content_block_location`

                    - `class BetaCitationWebSearchResultLocationParam`

                      - `cited_text: String`

                      - `encrypted_index: String`

                      - `title: String`

                      - `type: :web_search_result_location`

                        - `:web_search_result_location`

                      - `url: String`

                    - `class BetaCitationSearchResultLocationParam`

                      - `cited_text: String`

                        The full text of the cited block range, concatenated.

                        Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                      - `end_block_index: Integer`

                        Exclusive 0-based end index of the cited block range in the source's `content` array.

                        Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                      - `search_result_index: Integer`

                        0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                        Counted separately from `document_index`; server-side web search results are not included in this count.

                      - `source: String`

                      - `start_block_index: Integer`

                        0-based index of the first cited block in the source's `content` array.

                      - `title: String`

                      - `type: :search_result_location`

                        - `:search_result_location`

                - `class BetaImageBlockParam`

                  - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

                    - `class BetaBase64ImageSource`

                      - `data: String`

                      - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

                        - `:"image/jpeg"`

                        - `:"image/png"`

                        - `:"image/gif"`

                        - `:"image/webp"`

                      - `type: :base64`

                        - `:base64`

                    - `class BetaURLImageSource`

                      - `type: :url`

                        - `:url`

                      - `url: String`

                    - `class BetaFileImageSource`

                      - `file_id: String`

                      - `type: :file`

                        - `:file`

                  - `type: :image`

                    - `:image`

                  - `cache_control: BetaCacheControlEphemeral`

                    Create a cache control breakpoint at this content block.

            - `type: :content`

              - `:content`

          - `class BetaURLPDFSource`

            - `type: :url`

              - `:url`

            - `url: String`

          - `class BetaFileDocumentSource`

            - `file_id: String`

            - `type: :file`

              - `:file`

        - `type: :document`

          - `:document`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          - `enabled: bool`

        - `context: String`

        - `title: String`

      - `type: :web_fetch_result`

        - `:web_fetch_result`

      - `url: String`

        Fetched content URL

      - `retrieved_at: String`

        ISO 8601 timestamp when the content was retrieved

  - `tool_use_id: String`

  - `type: :web_fetch_tool_result`

    - `:web_fetch_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Web Fetch Tool Result Error Block

- `class BetaWebFetchToolResultErrorBlock`

  - `error_code: BetaWebFetchToolResultErrorCode`

    - `:invalid_tool_input`

    - `:url_too_long`

    - `:url_not_allowed`

    - `:url_not_in_prior_context`

    - `:url_not_accessible`

    - `:unsupported_content_type`

    - `:too_many_requests`

    - `:max_uses_exceeded`

    - `:unavailable`

  - `type: :web_fetch_tool_result_error`

    - `:web_fetch_tool_result_error`

### Beta Web Fetch Tool Result Error Block Param

- `class BetaWebFetchToolResultErrorBlockParam`

  - `error_code: BetaWebFetchToolResultErrorCode`

    - `:invalid_tool_input`

    - `:url_too_long`

    - `:url_not_allowed`

    - `:url_not_in_prior_context`

    - `:url_not_accessible`

    - `:unsupported_content_type`

    - `:too_many_requests`

    - `:max_uses_exceeded`

    - `:unavailable`

  - `type: :web_fetch_tool_result_error`

    - `:web_fetch_tool_result_error`

### Beta Web Fetch Tool Result Error Code

- `BetaWebFetchToolResultErrorCode = :invalid_tool_input | :url_too_long | :url_not_allowed | 6 more`

  - `:invalid_tool_input`

  - `:url_too_long`

  - `:url_not_allowed`

  - `:url_not_in_prior_context`

  - `:url_not_accessible`

  - `:unsupported_content_type`

  - `:too_many_requests`

  - `:max_uses_exceeded`

  - `:unavailable`

### Beta Web Search Result Block

- `class BetaWebSearchResultBlock`

  - `encrypted_content: String`

  - `page_age: String`

  - `title: String`

  - `type: :web_search_result`

    - `:web_search_result`

  - `url: String`

### Beta Web Search Result Block Param

- `class BetaWebSearchResultBlockParam`

  - `encrypted_content: String`

  - `title: String`

  - `type: :web_search_result`

    - `:web_search_result`

  - `url: String`

  - `page_age: String`

### Beta Web Search Tool 20250305

- `class BetaWebSearchTool20250305`

  - `name: :web_search`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:web_search`

  - `type: :web_search_20250305`

    - `:web_search_20250305`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `allowed_domains: Array[String]`

    If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

  - `blocked_domains: Array[String]`

    If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

  - `user_location: BetaUserLocation`

    Parameters for the user's location. Used to provide more relevant search results.

    - `type: :approximate`

      - `:approximate`

    - `city: String`

      The city of the user.

    - `country: String`

      The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

    - `region: String`

      The region of the user.

    - `timezone: String`

      The [IANA timezone](https://nodatime.org/TimeZones) of the user.

### Beta Web Search Tool 20260209

- `class BetaWebSearchTool20260209`

  - `name: :web_search`

    Name of the tool.

    This is how the tool will be called by the model and in `tool_use` blocks.

    - `:web_search`

  - `type: :web_search_20260209`

    - `:web_search_20260209`

  - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

    - `:direct`

    - `:code_execution_20250825`

    - `:code_execution_20260120`

  - `allowed_domains: Array[String]`

    If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

  - `blocked_domains: Array[String]`

    If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `defer_loading: bool`

    If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

  - `max_uses: Integer`

    Maximum number of times the tool can be used in the API request.

  - `strict: bool`

    When true, guarantees schema validation on tool names and inputs

  - `user_location: BetaUserLocation`

    Parameters for the user's location. Used to provide more relevant search results.

    - `type: :approximate`

      - `:approximate`

    - `city: String`

      The city of the user.

    - `country: String`

      The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

    - `region: String`

      The region of the user.

    - `timezone: String`

      The [IANA timezone](https://nodatime.org/TimeZones) of the user.

### Beta Web Search Tool Request Error

- `class BetaWebSearchToolRequestError`

  - `error_code: BetaWebSearchToolResultErrorCode`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:max_uses_exceeded`

    - `:too_many_requests`

    - `:query_too_long`

    - `:request_too_large`

  - `type: :web_search_tool_result_error`

    - `:web_search_tool_result_error`

### Beta Web Search Tool Result Block

- `class BetaWebSearchToolResultBlock`

  - `content: BetaWebSearchToolResultBlockContent`

    - `class BetaWebSearchToolResultError`

      - `error_code: BetaWebSearchToolResultErrorCode`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:max_uses_exceeded`

        - `:too_many_requests`

        - `:query_too_long`

        - `:request_too_large`

      - `type: :web_search_tool_result_error`

        - `:web_search_tool_result_error`

    - `UnionMember1 = Array[BetaWebSearchResultBlock]`

      - `encrypted_content: String`

      - `page_age: String`

      - `title: String`

      - `type: :web_search_result`

        - `:web_search_result`

      - `url: String`

  - `tool_use_id: String`

  - `type: :web_search_tool_result`

    - `:web_search_tool_result`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Web Search Tool Result Block Content

- `BetaWebSearchToolResultBlockContent = BetaWebSearchToolResultError | Array[BetaWebSearchResultBlock]`

  - `class BetaWebSearchToolResultError`

    - `error_code: BetaWebSearchToolResultErrorCode`

      - `:invalid_tool_input`

      - `:unavailable`

      - `:max_uses_exceeded`

      - `:too_many_requests`

      - `:query_too_long`

      - `:request_too_large`

    - `type: :web_search_tool_result_error`

      - `:web_search_tool_result_error`

  - `UnionMember1 = Array[BetaWebSearchResultBlock]`

    - `encrypted_content: String`

    - `page_age: String`

    - `title: String`

    - `type: :web_search_result`

      - `:web_search_result`

    - `url: String`

### Beta Web Search Tool Result Block Param

- `class BetaWebSearchToolResultBlockParam`

  - `content: BetaWebSearchToolResultBlockParamContent`

    - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

      - `encrypted_content: String`

      - `title: String`

      - `type: :web_search_result`

        - `:web_search_result`

      - `url: String`

      - `page_age: String`

    - `class BetaWebSearchToolRequestError`

      - `error_code: BetaWebSearchToolResultErrorCode`

        - `:invalid_tool_input`

        - `:unavailable`

        - `:max_uses_exceeded`

        - `:too_many_requests`

        - `:query_too_long`

        - `:request_too_large`

      - `type: :web_search_tool_result_error`

        - `:web_search_tool_result_error`

  - `tool_use_id: String`

  - `type: :web_search_tool_result`

    - `:web_search_tool_result`

  - `cache_control: BetaCacheControlEphemeral`

    Create a cache control breakpoint at this content block.

    - `type: :ephemeral`

      - `:ephemeral`

    - `ttl: :"5m" | :"1h"`

      The time-to-live for the cache control breakpoint.

      This may be one the following values:

      - `5m`: 5 minutes
      - `1h`: 1 hour

      Defaults to `5m`.

      - `:"5m"`

      - `:"1h"`

  - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

    Tool invocation directly from the model.

    - `class BetaDirectCaller`

      Tool invocation directly from the model.

      - `type: :direct`

        - `:direct`

    - `class BetaServerToolCaller`

      Tool invocation generated by a server-side tool.

      - `tool_id: String`

      - `type: :code_execution_20250825`

        - `:code_execution_20250825`

    - `class BetaServerToolCaller20260120`

      - `tool_id: String`

      - `type: :code_execution_20260120`

        - `:code_execution_20260120`

### Beta Web Search Tool Result Block Param Content

- `BetaWebSearchToolResultBlockParamContent = Array[BetaWebSearchResultBlockParam] | BetaWebSearchToolRequestError`

  - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

    - `encrypted_content: String`

    - `title: String`

    - `type: :web_search_result`

      - `:web_search_result`

    - `url: String`

    - `page_age: String`

  - `class BetaWebSearchToolRequestError`

    - `error_code: BetaWebSearchToolResultErrorCode`

      - `:invalid_tool_input`

      - `:unavailable`

      - `:max_uses_exceeded`

      - `:too_many_requests`

      - `:query_too_long`

      - `:request_too_large`

    - `type: :web_search_tool_result_error`

      - `:web_search_tool_result_error`

### Beta Web Search Tool Result Error

- `class BetaWebSearchToolResultError`

  - `error_code: BetaWebSearchToolResultErrorCode`

    - `:invalid_tool_input`

    - `:unavailable`

    - `:max_uses_exceeded`

    - `:too_many_requests`

    - `:query_too_long`

    - `:request_too_large`

  - `type: :web_search_tool_result_error`

    - `:web_search_tool_result_error`

### Beta Web Search Tool Result Error Code

- `BetaWebSearchToolResultErrorCode = :invalid_tool_input | :unavailable | :max_uses_exceeded | 3 more`

  - `:invalid_tool_input`

  - `:unavailable`

  - `:max_uses_exceeded`

  - `:too_many_requests`

  - `:query_too_long`

  - `:request_too_large`

# Batches

## Create a Message Batch

`beta.messages.batches.create(**kwargs) -> BetaMessageBatch`

**post** `/v1/messages/batches`

Send a batch of Message creation requests.

The Message Batches API can be used to process multiple Messages API requests at once. Once a Message Batch is created, it begins processing immediately. Batches can take up to 24 hours to complete.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `requests: Array[Request{ custom_id, params}]`

  List of requests for prompt completion. Each is an individual request to create a Message.

  - `custom_id: String`

    Developer-provided ID created for each request in a Message Batch. Useful for matching results to requests, as results may be given out of request order.

    Must be unique for each request within the Message Batch.

  - `params: Params{ max_tokens, messages, model, 23 more}`

    Messages API creation parameters for the individual request.

    See the [Messages API reference](https://docs.claude.com/en/api/messages) for full documentation on available parameters.

    - `max_tokens: Integer`

      The maximum number of tokens to generate before stopping.

      Note that our models may stop _before_ reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.

      Set to `0` to populate the [prompt cache](https://docs.claude.com/en/docs/build-with-claude/prompt-caching#pre-warming-the-cache) without generating a response.

      Different models have different maximum values for this parameter.  See [models](https://docs.claude.com/en/docs/models-overview) for details.

    - `messages: Array[BetaMessageParam]`

      Input messages.

      Our models are trained to operate on alternating `user` and `assistant` conversational turns. When creating a new `Message`, you specify the prior conversational turns with the `messages` parameter, and the model then generates the next `Message` in the conversation. Consecutive `user` or `assistant` turns in your request will be combined into a single turn.

      Each input message must be an object with a `role` and `content`. You can specify a single `user`-role message, or you can include multiple `user` and `assistant` messages.

      If the final message uses the `assistant` role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

      Example with a single `user` message:

      ```json
      [{"role": "user", "content": "Hello, Claude"}]
      ```

      Example with multiple conversational turns:

      ```json
      [
        {"role": "user", "content": "Hello there."},
        {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
        {"role": "user", "content": "Can you explain LLMs in plain English?"},
      ]
      ```

      Example with a partially-filled response from Claude:

      ```json
      [
        {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
        {"role": "assistant", "content": "The best answer is ("},
      ]
      ```

      Each input message `content` may be either a single `string` or an array of content blocks, where each block has a specific `type`. Using a `string` for `content` is shorthand for an array of one content block of type `"text"`. The following input messages are equivalent:

      ```json
      {"role": "user", "content": "Hello, Claude"}
      ```

      ```json
      {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}
      ```

      See [input examples](https://docs.claude.com/en/api/messages-examples).

      Note that if you want to include a [system prompt](https://docs.claude.com/en/docs/system-prompts), you can use the top-level `system` parameter — there is no `"system"` role for input messages in the Messages API.

      There is a limit of 100,000 messages in a single request.

      - `content: String | Array[BetaContentBlockParam]`

        - `String = String`

        - `UnionMember1 = Array[BetaContentBlockParam]`

          - `class BetaTextBlockParam`

            - `text: String`

            - `type: :text`

              - `:text`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

              - `type: :ephemeral`

                - `:ephemeral`

              - `ttl: :"5m" | :"1h"`

                The time-to-live for the cache control breakpoint.

                This may be one the following values:

                - `5m`: 5 minutes
                - `1h`: 1 hour

                Defaults to `5m`.

                - `:"5m"`

                - `:"1h"`

            - `citations: Array[BetaTextCitationParam]`

              - `class BetaCitationCharLocationParam`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_char_index: Integer`

                - `start_char_index: Integer`

                - `type: :char_location`

                  - `:char_location`

              - `class BetaCitationPageLocationParam`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_page_number: Integer`

                - `start_page_number: Integer`

                - `type: :page_location`

                  - `:page_location`

              - `class BetaCitationContentBlockLocationParam`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `document_index: Integer`

                - `document_title: String`

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `type: :content_block_location`

                  - `:content_block_location`

              - `class BetaCitationWebSearchResultLocationParam`

                - `cited_text: String`

                - `encrypted_index: String`

                - `title: String`

                - `type: :web_search_result_location`

                  - `:web_search_result_location`

                - `url: String`

              - `class BetaCitationSearchResultLocationParam`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `search_result_index: Integer`

                  0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from `document_index`; server-side web search results are not included in this count.

                - `source: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `title: String`

                - `type: :search_result_location`

                  - `:search_result_location`

          - `class BetaImageBlockParam`

            - `source: BetaBase64ImageSource | BetaURLImageSource | BetaFileImageSource`

              - `class BetaBase64ImageSource`

                - `data: String`

                - `media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"`

                  - `:"image/jpeg"`

                  - `:"image/png"`

                  - `:"image/gif"`

                  - `:"image/webp"`

                - `type: :base64`

                  - `:base64`

              - `class BetaURLImageSource`

                - `type: :url`

                  - `:url`

                - `url: String`

              - `class BetaFileImageSource`

                - `file_id: String`

                - `type: :file`

                  - `:file`

            - `type: :image`

              - `:image`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaRequestDocumentBlock`

            - `source: BetaBase64PDFSource | BetaPlainTextSource | BetaContentBlockSource | 2 more`

              - `class BetaBase64PDFSource`

                - `data: String`

                - `media_type: :"application/pdf"`

                  - `:"application/pdf"`

                - `type: :base64`

                  - `:base64`

              - `class BetaPlainTextSource`

                - `data: String`

                - `media_type: :"text/plain"`

                  - `:"text/plain"`

                - `type: :text`

                  - `:text`

              - `class BetaContentBlockSource`

                - `content: String | Array[BetaContentBlockSourceContent]`

                  - `String = String`

                  - `BetaContentBlockSourceContent = Array[BetaContentBlockSourceContent]`

                    - `class BetaTextBlockParam`

                    - `class BetaImageBlockParam`

                - `type: :content`

                  - `:content`

              - `class BetaURLPDFSource`

                - `type: :url`

                  - `:url`

                - `url: String`

              - `class BetaFileDocumentSource`

                - `file_id: String`

                - `type: :file`

                  - `:file`

            - `type: :document`

              - `:document`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `citations: BetaCitationsConfigParam`

              - `enabled: bool`

            - `context: String`

            - `title: String`

          - `class BetaSearchResultBlockParam`

            - `content: Array[BetaTextBlockParam]`

              - `text: String`

              - `type: :text`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

              - `citations: Array[BetaTextCitationParam]`

            - `source: String`

            - `title: String`

            - `type: :search_result`

              - `:search_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `citations: BetaCitationsConfigParam`

          - `class BetaThinkingBlockParam`

            - `signature: String`

            - `thinking: String`

            - `type: :thinking`

              - `:thinking`

          - `class BetaRedactedThinkingBlockParam`

            - `data: String`

            - `type: :redacted_thinking`

              - `:redacted_thinking`

          - `class BetaToolUseBlockParam`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

            - `type: :tool_use`

              - `:tool_use`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

                - `type: :direct`

                  - `:direct`

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

                - `tool_id: String`

                - `type: :code_execution_20250825`

                  - `:code_execution_20250825`

              - `class BetaServerToolCaller20260120`

                - `tool_id: String`

                - `type: :code_execution_20260120`

                  - `:code_execution_20260120`

          - `class BetaToolResultBlockParam`

            - `tool_use_id: String`

            - `type: :tool_result`

              - `:tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `content: String | Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

              - `String = String`

              - `Content = Array[BetaTextBlockParam | BetaImageBlockParam | BetaSearchResultBlockParam | 2 more]`

                - `class BetaTextBlockParam`

                - `class BetaImageBlockParam`

                - `class BetaSearchResultBlockParam`

                - `class BetaRequestDocumentBlock`

                - `class BetaToolReferenceBlockParam`

                  Tool reference block that can be included in tool_result content.

                  - `tool_name: String`

                  - `type: :tool_reference`

                    - `:tool_reference`

                  - `cache_control: BetaCacheControlEphemeral`

                    Create a cache control breakpoint at this content block.

            - `is_error: bool`

          - `class BetaServerToolUseBlockParam`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: :advisor | :web_search | :web_fetch | 5 more`

              - `:advisor`

              - `:web_search`

              - `:web_fetch`

              - `:code_execution`

              - `:bash_code_execution`

              - `:text_editor_code_execution`

              - `:tool_search_tool_regex`

              - `:tool_search_tool_bm25`

            - `type: :server_tool_use`

              - `:server_tool_use`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebSearchToolResultBlockParam`

            - `content: BetaWebSearchToolResultBlockParamContent`

              - `ResultBlock = Array[BetaWebSearchResultBlockParam]`

                - `encrypted_content: String`

                - `title: String`

                - `type: :web_search_result`

                  - `:web_search_result`

                - `url: String`

                - `page_age: String`

              - `class BetaWebSearchToolRequestError`

                - `error_code: BetaWebSearchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:max_uses_exceeded`

                  - `:too_many_requests`

                  - `:query_too_long`

                  - `:request_too_large`

                - `type: :web_search_tool_result_error`

                  - `:web_search_tool_result_error`

            - `tool_use_id: String`

            - `type: :web_search_tool_result`

              - `:web_search_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebFetchToolResultBlockParam`

            - `content: BetaWebFetchToolResultErrorBlockParam | BetaWebFetchBlockParam`

              - `class BetaWebFetchToolResultErrorBlockParam`

                - `error_code: BetaWebFetchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:url_too_long`

                  - `:url_not_allowed`

                  - `:url_not_in_prior_context`

                  - `:url_not_accessible`

                  - `:unsupported_content_type`

                  - `:too_many_requests`

                  - `:max_uses_exceeded`

                  - `:unavailable`

                - `type: :web_fetch_tool_result_error`

                  - `:web_fetch_tool_result_error`

              - `class BetaWebFetchBlockParam`

                - `content: BetaRequestDocumentBlock`

                - `type: :web_fetch_result`

                  - `:web_fetch_result`

                - `url: String`

                  Fetched content URL

                - `retrieved_at: String`

                  ISO 8601 timestamp when the content was retrieved

            - `tool_use_id: String`

            - `type: :web_fetch_tool_result`

              - `:web_fetch_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaAdvisorToolResultBlockParam`

            - `content: BetaAdvisorToolResultErrorParam | BetaAdvisorResultBlockParam | BetaAdvisorRedactedResultBlockParam`

              - `class BetaAdvisorToolResultErrorParam`

                - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

                  - `:max_uses_exceeded`

                  - `:prompt_too_long`

                  - `:too_many_requests`

                  - `:overloaded`

                  - `:unavailable`

                  - `:execution_time_exceeded`

                  - `:model_not_found`

                - `type: :advisor_tool_result_error`

                  - `:advisor_tool_result_error`

              - `class BetaAdvisorResultBlockParam`

                - `text: String`

                - `type: :advisor_result`

                  - `:advisor_result`

                - `stop_reason: String`

              - `class BetaAdvisorRedactedResultBlockParam`

                - `encrypted_content: String`

                  Opaque blob produced by a prior response; must be round-tripped verbatim.

                - `type: :advisor_redacted_result`

                  - `:advisor_redacted_result`

                - `stop_reason: String`

            - `tool_use_id: String`

            - `type: :advisor_tool_result`

              - `:advisor_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaCodeExecutionToolResultBlockParam`

            - `content: BetaCodeExecutionToolResultBlockParamContent`

              Code execution result with encrypted stdout for PFC + web_search results.

              - `class BetaCodeExecutionToolResultErrorParam`

                - `error_code: BetaCodeExecutionToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `type: :code_execution_tool_result_error`

                  - `:code_execution_tool_result_error`

              - `class BetaCodeExecutionResultBlockParam`

                - `content: Array[BetaCodeExecutionOutputBlockParam]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                    - `:code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :code_execution_result`

                  - `:code_execution_result`

              - `class BetaEncryptedCodeExecutionResultBlockParam`

                Code execution result with encrypted stdout for PFC + web_search results.

                - `content: Array[BetaCodeExecutionOutputBlockParam]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                - `encrypted_stdout: String`

                - `return_code: Integer`

                - `stderr: String`

                - `type: :encrypted_code_execution_result`

                  - `:encrypted_code_execution_result`

            - `tool_use_id: String`

            - `type: :code_execution_tool_result`

              - `:code_execution_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaBashCodeExecutionToolResultBlockParam`

            - `content: BetaBashCodeExecutionToolResultErrorParam | BetaBashCodeExecutionResultBlockParam`

              - `class BetaBashCodeExecutionToolResultErrorParam`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:output_file_too_large`

                - `type: :bash_code_execution_tool_result_error`

                  - `:bash_code_execution_tool_result_error`

              - `class BetaBashCodeExecutionResultBlockParam`

                - `content: Array[BetaBashCodeExecutionOutputBlockParam]`

                  - `file_id: String`

                  - `type: :bash_code_execution_output`

                    - `:bash_code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :bash_code_execution_result`

                  - `:bash_code_execution_result`

            - `tool_use_id: String`

            - `type: :bash_code_execution_tool_result`

              - `:bash_code_execution_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaTextEditorCodeExecutionToolResultBlockParam`

            - `content: BetaTextEditorCodeExecutionToolResultErrorParam | BetaTextEditorCodeExecutionViewResultBlockParam | BetaTextEditorCodeExecutionCreateResultBlockParam | BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

              - `class BetaTextEditorCodeExecutionToolResultErrorParam`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:file_not_found`

                - `type: :text_editor_code_execution_tool_result_error`

                  - `:text_editor_code_execution_tool_result_error`

                - `error_message: String`

              - `class BetaTextEditorCodeExecutionViewResultBlockParam`

                - `content: String`

                - `file_type: :text | :image | :pdf`

                  - `:text`

                  - `:image`

                  - `:pdf`

                - `type: :text_editor_code_execution_view_result`

                  - `:text_editor_code_execution_view_result`

                - `num_lines: Integer`

                - `start_line: Integer`

                - `total_lines: Integer`

              - `class BetaTextEditorCodeExecutionCreateResultBlockParam`

                - `is_file_update: bool`

                - `type: :text_editor_code_execution_create_result`

                  - `:text_editor_code_execution_create_result`

              - `class BetaTextEditorCodeExecutionStrReplaceResultBlockParam`

                - `type: :text_editor_code_execution_str_replace_result`

                  - `:text_editor_code_execution_str_replace_result`

                - `lines: Array[String]`

                - `new_lines: Integer`

                - `new_start: Integer`

                - `old_lines: Integer`

                - `old_start: Integer`

            - `tool_use_id: String`

            - `type: :text_editor_code_execution_tool_result`

              - `:text_editor_code_execution_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaToolSearchToolResultBlockParam`

            - `content: BetaToolSearchToolResultErrorParam | BetaToolSearchToolSearchResultBlockParam`

              - `class BetaToolSearchToolResultErrorParam`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `type: :tool_search_tool_result_error`

                  - `:tool_search_tool_result_error`

                - `error_message: String`

              - `class BetaToolSearchToolSearchResultBlockParam`

                - `tool_references: Array[BetaToolReferenceBlockParam]`

                  - `tool_name: String`

                  - `type: :tool_reference`

                  - `cache_control: BetaCacheControlEphemeral`

                    Create a cache control breakpoint at this content block.

                - `type: :tool_search_tool_search_result`

                  - `:tool_search_tool_search_result`

            - `tool_use_id: String`

            - `type: :tool_search_tool_result`

              - `:tool_search_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaMCPToolUseBlockParam`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

            - `server_name: String`

              The name of the MCP server

            - `type: :mcp_tool_use`

              - `:mcp_tool_use`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaRequestMCPToolResultBlockParam`

            - `tool_use_id: String`

            - `type: :mcp_tool_result`

              - `:mcp_tool_result`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `content: String | Array[BetaTextBlockParam]`

              - `String = String`

              - `BetaMCPToolResultBlockParamContent = Array[BetaTextBlockParam]`

                - `text: String`

                - `type: :text`

                - `cache_control: BetaCacheControlEphemeral`

                  Create a cache control breakpoint at this content block.

                - `citations: Array[BetaTextCitationParam]`

            - `is_error: bool`

          - `class BetaContainerUploadBlockParam`

            A content block that represents a file to be uploaded to the container
            Files uploaded via this block will be available in the container's input directory.

            - `file_id: String`

            - `type: :container_upload`

              - `:container_upload`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaCompactionBlockParam`

            A compaction block containing summary of previous context.

            Users should round-trip these blocks from responses to subsequent requests
            to maintain context across compaction boundaries.

            When content is None, the block represents a failed compaction. The server
            treats these as no-ops. Empty string content is not allowed.

            - `type: :compaction`

              - `:compaction`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

            - `content: String`

              Summary of previously compacted content, or null if compaction failed

            - `encrypted_content: String`

              Opaque metadata from prior compaction, to be round-tripped verbatim

          - `class BetaMidConversationSystemBlockParam`

            System instructions that appear mid-conversation.

            Use this block to provide or update system-level instructions at a specific
            point in the conversation, rather than only via the top-level `system` parameter.

            - `content: Array[BetaTextBlockParam]`

              System instruction text blocks.

              - `text: String`

              - `type: :text`

              - `cache_control: BetaCacheControlEphemeral`

                Create a cache control breakpoint at this content block.

              - `citations: Array[BetaTextCitationParam]`

            - `type: :mid_conv_system`

              - `:mid_conv_system`

            - `cache_control: BetaCacheControlEphemeral`

              Create a cache control breakpoint at this content block.

          - `class BetaFallbackBlockParam`

            A `fallback` block echoed back from a prior response.

            Accepted in `messages[].content` and never rendered into the prompt,
            not validated against the request's `fallbacks` chain or top-level
            `model`, and stripped before the sticky-routing cache key is computed.

            Callers should echo the assistant turn verbatim — block included. The
            block's position is load-bearing for thinking verification: the thinking
            runs on either side of a fallback hop carry independently-rooted
            verification hash chains, and this block is the only record of where one
            chain ends and the next begins. When thinking runs flank the boundary,
            omitting the block merges the runs into one contiguous span whose hashes
            cannot verify (the request is rejected), and moving it into the middle of
            a single run splits that run's chain and is likewise rejected; between
            non-thinking blocks the block's placement has no verification effect.

            - `from: BetaFallbackInfoParam`

              Identifies one hop of a fallback transition.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

                  The model that will complete your prompt.

                  See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                  - `:"claude-fable-5"`

                    Next generation of intelligence for the hardest knowledge work and coding problems

                  - `:"claude-mythos-5"`

                    Most capable model for cybersecurity and biology research

                  - `:"claude-opus-4-8"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-opus-4-7"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-mythos-preview"`

                    New class of intelligence, strongest in coding and cybersecurity

                  - `:"claude-opus-4-6"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-sonnet-4-6"`

                    Best combination of speed and intelligence

                  - `:"claude-haiku-4-5"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-haiku-4-5-20251001"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-opus-4-5"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-opus-4-5-20251101"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-sonnet-4-5"`

                    High-performance model for agents and coding

                  - `:"claude-sonnet-4-5-20250929"`

                    High-performance model for agents and coding

                  - `:"claude-opus-4-1"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-1-20250805"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-0"`

                    Powerful model for complex tasks

                  - `:"claude-opus-4-20250514"`

                    Powerful model for complex tasks

                  - `:"claude-sonnet-4-0"`

                    High-performance model with extended thinking

                  - `:"claude-sonnet-4-20250514"`

                    High-performance model with extended thinking

                  - `:"claude-3-haiku-20240307"`

                    Fast and cost-effective model

                - `String = String`

            - `to: BetaFallbackInfoParam`

              Identifies one hop of a fallback transition.

            - `type: :fallback`

              - `:fallback`

      - `role: :user | :assistant | :system`

        - `:user`

        - `:assistant`

        - `:system`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `cache_control: BetaCacheControlEphemeral`

      Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

    - `container: BetaContainerParams | String`

      Container identifier for reuse across requests.

      - `class BetaContainerParams`

        Container parameters with skills to be loaded.

        - `id: String`

          Container id

        - `skills: Array[BetaSkillParams]`

          List of skills to load in the container

          - `skill_id: String`

            Skill ID

          - `type: :anthropic | :custom`

            Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

            - `:anthropic`

            - `:custom`

          - `version: String`

            Skill version or 'latest' for most recent version

      - `String = String`

    - `context_management: BetaContextManagementConfig`

      Context management configuration.

      This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

      - `edits: Array[BetaClearToolUses20250919Edit | BetaClearThinking20251015Edit | BetaCompact20260112Edit]`

        List of context management edits to apply

        - `class BetaClearToolUses20250919Edit`

          - `type: :clear_tool_uses_20250919`

            - `:clear_tool_uses_20250919`

          - `clear_at_least: BetaInputTokensClearAtLeast`

            Minimum number of tokens that must be cleared when triggered. Context will only be modified if at least this many tokens can be removed.

            - `type: :input_tokens`

              - `:input_tokens`

            - `value: Integer`

          - `clear_tool_inputs: bool | Array[String]`

            Whether to clear all tool inputs (bool) or specific tool inputs to clear (list)

            - `UnionMember0 = bool`

            - `UnionMember1 = Array[String]`

          - `exclude_tools: Array[String]`

            Tool names whose uses are preserved from clearing

          - `keep: BetaToolUsesKeep`

            Number of tool uses to retain in the conversation

            - `type: :tool_uses`

              - `:tool_uses`

            - `value: Integer`

          - `trigger: BetaInputTokensTrigger | BetaToolUsesTrigger`

            Condition that triggers the context management strategy

            - `class BetaInputTokensTrigger`

              - `type: :input_tokens`

                - `:input_tokens`

              - `value: Integer`

            - `class BetaToolUsesTrigger`

              - `type: :tool_uses`

                - `:tool_uses`

              - `value: Integer`

        - `class BetaClearThinking20251015Edit`

          - `type: :clear_thinking_20251015`

            - `:clear_thinking_20251015`

          - `keep: BetaThinkingTurns | BetaAllThinkingTurns | :all`

            Number of most recent assistant turns to keep thinking blocks for. Older turns will have their thinking blocks removed.

            - `class BetaThinkingTurns`

              - `type: :thinking_turns`

                - `:thinking_turns`

              - `value: Integer`

            - `class BetaAllThinkingTurns`

              - `type: :all`

                - `:all`

            - `Keep = :all`

              - `:all`

        - `class BetaCompact20260112Edit`

          Automatically compact older context when reaching the configured trigger threshold.

          - `type: :compact_20260112`

            - `:compact_20260112`

          - `instructions: String`

            Additional instructions for summarization.

          - `pause_after_compaction: bool`

            Whether to pause after compaction and return the compaction block to the user.

          - `trigger: BetaInputTokensTrigger`

            When to trigger compaction. Defaults to 150000 input tokens.

    - `diagnostics: BetaDiagnosticsParam`

      Request-level diagnostics. Currently carries the previous response
      id for prompt-cache divergence reporting.

      - `previous_message_id: String`

        The `id` (`msg_...`) from this client's previous /v1/messages response. The server compares that request's prompt fingerprint against this one and returns `diagnostics.cache_miss_reason` when the prompt-cache prefix could not be reused. Pass `null` on the first turn to opt in without a prior message to compare.

    - `fallback_credit_token: String`

      The `fallback_credit_token` from a prior refusal's `stop_details`.

      When a preceding request was refused and returned a `fallback_credit_token`,
      pass that code here on the retry to have the retry's cache-creation tokens
      for the prefix that was warm on the refused model billed at the cache-read
      rate. Must be redeemed by the same organization and workspace, with the same
      request body (optionally extended by one appended `assistant` message whose
      content is the partial text — with any trailing whitespace stripped from
      the final text block — and paired server-tool blocks streamed before the
      refusal; the appended-assistant form is not available for requests with
      `output_format` set or forced `tool_choice`), on an eligible fallback
      model, on the same platform,
      and within 5 minutes of the refusal; a mismatch is a 400. A token minted
      mid-server-tool-loop whose partial content was continuable may only be
      redeemed with the appended-assistant form — if an exact-body retry is
      rejected with a 400 saying the token must be redeemed by continuing the
      partial response, retry with the appended-assistant form instead.

      When the appended-assistant form is used on a model that otherwise disallows
      assistant-turn prefill, this token also authorizes that one prefill.

    - `fallbacks: Array[BetaFallbackParam]`

      Opt-in server-side retry on one or more substitute models when the requested model declines for policy reasons. Tried in order: if the first entry also declines, the second is tried, and so on.

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `max_tokens: Integer`

      - `output_config: BetaOutputConfig`

        - `effort: :low | :medium | :high | 2 more`

          All possible effort levels.

          - `:low`

          - `:medium`

          - `:high`

          - `:xhigh`

          - `:max`

        - `format_: BetaJSONOutputFormat`

          A schema to specify Claude's output format in responses. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

          - `schema: Hash[Symbol, untyped]`

            The JSON schema of the format

          - `type: :json_schema`

            - `:json_schema`

        - `task_budget: BetaTokenTaskBudget`

          User-configurable total token budget across contexts.

          - `total: Integer`

            Total token budget across all contexts in the session.

          - `type: :tokens`

            The budget type. Currently only 'tokens' is supported.

            - `:tokens`

          - `remaining: Integer`

            Remaining tokens in the budget. Use this to track usage across contexts when implementing compaction client-side. Defaults to total if not provided.

      - `speed: :standard | :fast`

        - `:standard`

        - `:fast`

      - `thinking: BetaThinkingConfigEnabled | BetaThinkingConfigDisabled | BetaThinkingConfigAdaptive`

        - `class BetaThinkingConfigEnabled`

          - `budget_tokens: Integer`

            Determines how many tokens Claude can use for its internal reasoning process. Larger budgets can enable more thorough analysis for complex problems, improving response quality.

            Must be ≥1024 and less than `max_tokens`.

            See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

          - `type: :enabled`

            - `:enabled`

          - `display_: :summarized | :omitted`

            Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

            - `:summarized`

            - `:omitted`

        - `class BetaThinkingConfigDisabled`

          - `type: :disabled`

            - `:disabled`

        - `class BetaThinkingConfigAdaptive`

          - `type: :adaptive`

            - `:adaptive`

          - `display_: :summarized | :omitted`

            Controls how thinking content appears in the response. When set to `summarized`, thinking is returned normally. When set to `omitted`, thinking content is redacted but a signature is returned for multi-turn continuity. Defaults to `summarized`.

            - `:summarized`

            - `:omitted`

    - `inference_geo: String`

      Specifies the geographic region for inference processing. If not specified, the workspace's `default_inference_geo` is used.

    - `mcp_servers: Array[BetaRequestMCPServerURLDefinition]`

      MCP servers to be utilized in this request

      - `name: String`

      - `type: :url`

        - `:url`

      - `url: String`

      - `authorization_token: String`

      - `tool_configuration: BetaRequestMCPServerToolConfiguration`

        - `allowed_tools: Array[String]`

        - `enabled: bool`

    - `metadata: BetaMetadata`

      An object describing metadata about the request.

      - `user_id: String`

        An external identifier for the user who is associated with the request.

        This should be a uuid, hash value, or other opaque identifier. Anthropic may use this id to help detect abuse. Do not include any identifying information such as name, email address, or phone number.

    - `output_config: BetaOutputConfig`

      Configuration options for the model's output, such as the output format.

    - `output_format: BetaJSONOutputFormat`

      Deprecated: Use `output_config.format` instead. See [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

      A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

    - `service_tier: :auto | :standard_only`

      Determines whether to use priority capacity (if available) or standard capacity for this request.

      Anthropic offers different levels of service for your API requests. See [service-tiers](https://docs.claude.com/en/api/service-tiers) for details.

      - `:auto`

      - `:standard_only`

    - `speed: :standard | :fast`

      The inference speed mode for this request. `"fast"` enables high output-tokens-per-second inference.

      - `:standard`

      - `:fast`

    - `stop_sequences: Array[String]`

      Custom text sequences that will cause the model to stop generating.

      Our models will normally stop when they have naturally completed their turn, which will result in a response `stop_reason` of `"end_turn"`.

      If you want the model to stop generating when it encounters custom strings of text, you can use the `stop_sequences` parameter. If the model encounters one of the custom sequences, the response `stop_reason` value will be `"stop_sequence"` and the response `stop_sequence` value will contain the matched stop sequence.

    - `stream: bool`

      Whether to incrementally stream the response using server-sent events.

      See [streaming](https://docs.claude.com/en/api/messages-streaming) for details.

    - `system_: String | Array[BetaTextBlockParam]`

      System prompt.

      A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our [guide to system prompts](https://docs.claude.com/en/docs/system-prompts).

      - `String = String`

      - `UnionMember1 = Array[BetaTextBlockParam]`

        - `text: String`

        - `type: :text`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: Array[BetaTextCitationParam]`

    - `temperature: Float`

      Amount of randomness injected into the response.

      Defaults to `1.0`. Ranges from `0.0` to `1.0`. Use `temperature` closer to `0.0` for analytical / multiple choice, and closer to `1.0` for creative and generative tasks.

      Note that even with `temperature` of `0.0`, the results will not be fully deterministic.

    - `thinking: BetaThinkingConfigParam`

      Configuration for enabling Claude's extended thinking.

      When enabled, responses include `thinking` content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your `max_tokens` limit.

      See [extended thinking](https://docs.claude.com/en/docs/build-with-claude/extended-thinking) for details.

      - `class BetaThinkingConfigEnabled`

      - `class BetaThinkingConfigDisabled`

      - `class BetaThinkingConfigAdaptive`

    - `tool_choice: BetaToolChoice`

      How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

      - `class BetaToolChoiceAuto`

        The model will automatically decide whether to use tools.

        - `type: :auto`

          - `:auto`

        - `disable_parallel_tool_use: bool`

          Whether to disable parallel tool use.

          Defaults to `false`. If set to `true`, the model will output at most one tool use.

      - `class BetaToolChoiceAny`

        The model will use any available tools.

        - `type: :any`

          - `:any`

        - `disable_parallel_tool_use: bool`

          Whether to disable parallel tool use.

          Defaults to `false`. If set to `true`, the model will output exactly one tool use.

      - `class BetaToolChoiceTool`

        The model will use the specified tool with `tool_choice.name`.

        - `name: String`

          The name of the tool to use.

        - `type: :tool`

          - `:tool`

        - `disable_parallel_tool_use: bool`

          Whether to disable parallel tool use.

          Defaults to `false`. If set to `true`, the model will output exactly one tool use.

      - `class BetaToolChoiceNone`

        The model will not be allowed to use tools.

        - `type: :none`

          - `:none`

    - `tools: Array[BetaToolUnion]`

      Definitions of tools that the model may use.

      If you include `tools` in your API request, the model may return `tool_use` content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using `tool_result` content blocks.

      There are two types of tools: **client tools** and **server tools**. The behavior described below applies to client tools. For [server tools](https://docs.claude.com/en/docs/agents-and-tools/tool-use/overview#server-tools), see their individual documentation as each has its own behavior (e.g., the [web search tool](https://docs.claude.com/en/docs/agents-and-tools/tool-use/web-search-tool)).

      Each tool definition includes:

      * `name`: Name of the tool.
      * `description`: Optional, but strongly-recommended description of the tool.
      * `input_schema`: [JSON schema](https://json-schema.org/draft/2020-12) for the tool `input` shape that the model will produce in `tool_use` output content blocks.

      For example, if you defined `tools` as:

      ```json
      [
        {
          "name": "get_stock_price",
          "description": "Get the current stock price for a given ticker symbol.",
          "input_schema": {
            "type": "object",
            "properties": {
              "ticker": {
                "type": "string",
                "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
              }
            },
            "required": ["ticker"]
          }
        }
      ]
      ```

      And then asked the model "What's the S&P 500 at today?", the model might produce `tool_use` content blocks in the response like this:

      ```json
      [
        {
          "type": "tool_use",
          "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
          "name": "get_stock_price",
          "input": { "ticker": "^GSPC" }
        }
      ]
      ```

      You might then run your `get_stock_price` tool with `{"ticker": "^GSPC"}` as an input, and return the following back to the model in a subsequent `user` message:

      ```json
      [
        {
          "type": "tool_result",
          "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
          "content": "259.75 USD"
        }
      ]
      ```

      Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

      See our [guide](https://docs.claude.com/en/docs/tool-use) for more details.

      - `class BetaTool`

        - `input_schema: InputSchema{ type, properties, required}`

          [JSON schema](https://json-schema.org/draft/2020-12) for this tool's input.

          This defines the shape of the `input` that your tool accepts and that the model will produce.

          - `type: :object`

            - `:object`

          - `properties: Hash[Symbol, untyped]`

          - `required: Array[String]`

        - `name: String`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `description: String`

          Description of what this tool does.

          Tool descriptions should be as detailed as possible. The more information that the model has about what the tool is and how to use it, the better it will perform. You can use natural language descriptions to reinforce important aspects of the tool input JSON schema.

        - `eager_input_streaming: bool`

          Enable eager input streaming for this tool. When true, tool input parameters will be streamed incrementally as they are generated, and types will be inferred on-the-fly rather than buffering the full JSON output. When false, streaming is disabled for this tool even if the fine-grained-tool-streaming beta is active. When null (default), uses the default behavior based on beta headers.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

        - `type: :custom`

          - `:custom`

      - `class BetaToolBash20241022`

        - `name: :bash`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:bash`

        - `type: :bash_20241022`

          - `:bash_20241022`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolBash20250124`

        - `name: :bash`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:bash`

        - `type: :bash_20250124`

          - `:bash_20250124`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaCodeExecutionTool20250522`

        - `name: :code_execution`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:code_execution`

        - `type: :code_execution_20250522`

          - `:code_execution_20250522`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaCodeExecutionTool20250825`

        - `name: :code_execution`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:code_execution`

        - `type: :code_execution_20250825`

          - `:code_execution_20250825`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaCodeExecutionTool20260120`

        Code execution tool with REPL state persistence (daemon mode + gVisor checkpoint).

        - `name: :code_execution`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:code_execution`

        - `type: :code_execution_20260120`

          - `:code_execution_20260120`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolComputerUse20241022`

        - `display_height_px: Integer`

          The height of the display in pixels.

        - `display_width_px: Integer`

          The width of the display in pixels.

        - `name: :computer`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:computer`

        - `type: :computer_20241022`

          - `:computer_20241022`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `display_number: Integer`

          The X11 display number (e.g. 0, 1) for the display.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaMemoryTool20250818`

        - `name: :memory`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:memory`

        - `type: :memory_20250818`

          - `:memory_20250818`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolComputerUse20250124`

        - `display_height_px: Integer`

          The height of the display in pixels.

        - `display_width_px: Integer`

          The width of the display in pixels.

        - `name: :computer`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:computer`

        - `type: :computer_20250124`

          - `:computer_20250124`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `display_number: Integer`

          The X11 display number (e.g. 0, 1) for the display.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolTextEditor20241022`

        - `name: :str_replace_editor`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:str_replace_editor`

        - `type: :text_editor_20241022`

          - `:text_editor_20241022`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolComputerUse20251124`

        - `display_height_px: Integer`

          The height of the display in pixels.

        - `display_width_px: Integer`

          The width of the display in pixels.

        - `name: :computer`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:computer`

        - `type: :computer_20251124`

          - `:computer_20251124`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `display_number: Integer`

          The X11 display number (e.g. 0, 1) for the display.

        - `enable_zoom: bool`

          Whether to enable an action to take a zoomed-in screenshot of the screen.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolTextEditor20250124`

        - `name: :str_replace_editor`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:str_replace_editor`

        - `type: :text_editor_20250124`

          - `:text_editor_20250124`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolTextEditor20250429`

        - `name: :str_replace_based_edit_tool`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:str_replace_based_edit_tool`

        - `type: :text_editor_20250429`

          - `:text_editor_20250429`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolTextEditor20250728`

        - `name: :str_replace_based_edit_tool`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:str_replace_based_edit_tool`

        - `type: :text_editor_20250728`

          - `:text_editor_20250728`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `input_examples: Array[Hash[Symbol, untyped]]`

        - `max_characters: Integer`

          Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaWebSearchTool20250305`

        - `name: :web_search`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:web_search`

        - `type: :web_search_20250305`

          - `:web_search_20250305`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `allowed_domains: Array[String]`

          If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

        - `blocked_domains: Array[String]`

          If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

        - `user_location: BetaUserLocation`

          Parameters for the user's location. Used to provide more relevant search results.

          - `type: :approximate`

            - `:approximate`

          - `city: String`

            The city of the user.

          - `country: String`

            The two letter [ISO country code](https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2) of the user.

          - `region: String`

            The region of the user.

          - `timezone: String`

            The [IANA timezone](https://nodatime.org/TimeZones) of the user.

      - `class BetaWebFetchTool20250910`

        - `name: :web_fetch`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:web_fetch`

        - `type: :web_fetch_20250910`

          - `:web_fetch_20250910`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `allowed_domains: Array[String]`

          List of domains to allow fetching from

        - `blocked_domains: Array[String]`

          List of domains to block fetching from

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          Citations configuration for fetched documents. Citations are disabled by default.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_content_tokens: Integer`

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaWebSearchTool20260209`

        - `name: :web_search`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:web_search`

        - `type: :web_search_20260209`

          - `:web_search_20260209`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `allowed_domains: Array[String]`

          If provided, only these domains will be included in results. Cannot be used alongside `blocked_domains`.

        - `blocked_domains: Array[String]`

          If provided, these domains will never appear in results. Cannot be used alongside `allowed_domains`.

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

        - `user_location: BetaUserLocation`

          Parameters for the user's location. Used to provide more relevant search results.

      - `class BetaWebFetchTool20260209`

        - `name: :web_fetch`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:web_fetch`

        - `type: :web_fetch_20260209`

          - `:web_fetch_20260209`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `allowed_domains: Array[String]`

          List of domains to allow fetching from

        - `blocked_domains: Array[String]`

          List of domains to block fetching from

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          Citations configuration for fetched documents. Citations are disabled by default.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_content_tokens: Integer`

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaWebFetchTool20260309`

        Web fetch tool with use_cache parameter for bypassing cached content.

        - `name: :web_fetch`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:web_fetch`

        - `type: :web_fetch_20260309`

          - `:web_fetch_20260309`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `allowed_domains: Array[String]`

          List of domains to allow fetching from

        - `blocked_domains: Array[String]`

          List of domains to block fetching from

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `citations: BetaCitationsConfigParam`

          Citations configuration for fetched documents. Citations are disabled by default.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_content_tokens: Integer`

          Maximum number of tokens used by including web page text content in the context. The limit is approximate and does not apply to binary content such as PDFs.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

        - `use_cache: bool`

          Whether to use cached content. Set to false to bypass the cache and fetch fresh content. Only set to false when the user explicitly requests fresh content or when fetching rapidly-changing sources.

      - `class BetaAdvisorTool20260301`

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `name: :advisor`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:advisor`

        - `type: :advisor_20260301`

          - `:advisor_20260301`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `caching: BetaCacheControlEphemeral`

          Caching for the advisor's own prompt. When set, each advisor call writes a cache entry at the given TTL so subsequent calls in the same conversation read the stable prefix. When omitted, the advisor prompt is not cached.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `max_tokens: Integer`

          Bounds the advisor's total output (thinking + text) per call. When the advisor hits this cap, the returned advisor_result or advisor_redacted_result block carries stop_reason='max_tokens', and a truncation note is appended to the advice text the worker model sees (inside the encrypted blob in redacted mode). When set, the server also emits a remaining-tokens budget block in the advisor's prompt so the advisor self-shapes toward the cap. When omitted, the advisor model's default output cap applies and no budget block is emitted.

        - `max_uses: Integer`

          Maximum number of times the tool can be used in the API request.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolSearchToolBm25_20251119`

        - `name: :tool_search_tool_bm25`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:tool_search_tool_bm25`

        - `type: :tool_search_tool_bm25_20251119 | :tool_search_tool_bm25`

          - `:tool_search_tool_bm25_20251119`

          - `:tool_search_tool_bm25`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaToolSearchToolRegex20251119`

        - `name: :tool_search_tool_regex`

          Name of the tool.

          This is how the tool will be called by the model and in `tool_use` blocks.

          - `:tool_search_tool_regex`

        - `type: :tool_search_tool_regex_20251119 | :tool_search_tool_regex`

          - `:tool_search_tool_regex_20251119`

          - `:tool_search_tool_regex`

        - `allowed_callers: Array[:direct | :code_execution_20250825 | :code_execution_20260120]`

          - `:direct`

          - `:code_execution_20250825`

          - `:code_execution_20260120`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `defer_loading: bool`

          If true, tool will not be included in initial system prompt. Only loaded when returned via tool_reference from tool search.

        - `strict: bool`

          When true, guarantees schema validation on tool names and inputs

      - `class BetaMCPToolset`

        Configuration for a group of tools from an MCP server.

        Allows configuring enabled status and defer_loading for all tools
        from an MCP server, with optional per-tool overrides.

        - `mcp_server_name: String`

          Name of the MCP server to configure tools for

        - `type: :mcp_toolset`

          - `:mcp_toolset`

        - `cache_control: BetaCacheControlEphemeral`

          Create a cache control breakpoint at this content block.

        - `configs: Hash[Symbol, BetaMCPToolConfig]`

          Configuration overrides for specific tools, keyed by tool name

          - `defer_loading: bool`

          - `enabled: bool`

        - `default_config: BetaMCPToolDefaultConfig`

          Default configuration applied to all tools from this server

          - `defer_loading: bool`

          - `enabled: bool`

    - `top_k: Integer`

      Only sample from the top K options for each subsequent token.

      Used to remove "long tail" low probability responses. [Learn more technical details here](https://towardsdatascience.com/how-to-sample-from-language-models-682bceb97277).

      Recommended for advanced use cases only.

    - `top_p: Float`

      Use nucleus sampling.

      In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by `top_p`.

      Recommended for advanced use cases only.

    - `user_profile_id: String`

      The user profile ID to attribute this request to. Use when acting on behalf of a party other than your organization.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageBatch`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `archived_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

  - `cancel_initiated_at: Time`

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

  - `created_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was created.

  - `ended_at: Time`

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

  - `expires_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

  - `processing_status: :in_progress | :canceling | :ended`

    Processing status of the Message Batch.

    - `:in_progress`

    - `:canceling`

    - `:ended`

  - `request_counts: BetaMessageBatchRequestCounts`

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as `processing` and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    - `canceled: Integer`

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

    - `errored: Integer`

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

    - `expired: Integer`

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

    - `processing: Integer`

      Number of requests in the Message Batch that are processing.

    - `succeeded: Integer`

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

  - `results_url: String`

    URL to a `.jsonl` file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

  - `type: :message_batch`

    Object type.

    For Message Batches, this is always `"message_batch"`.

    - `:message_batch`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message_batch = anthropic.beta.messages.batches.create(
  requests: [
    {
      custom_id: "my-custom-id-1",
      params: {max_tokens: 1024, messages: [{content: "Hello, world", role: :user}], model: :"claude-opus-4-6"}
    }
  ]
)

puts(beta_message_batch)
```

#### Response

```json
{
  "id": "msgbatch_013Zva2CMHLNnXjNJJKqJ2EF",
  "archived_at": "2024-08-20T18:37:24.100435Z",
  "cancel_initiated_at": "2024-08-20T18:37:24.100435Z",
  "created_at": "2024-08-20T18:37:24.100435Z",
  "ended_at": "2024-08-20T18:37:24.100435Z",
  "expires_at": "2024-08-20T18:37:24.100435Z",
  "processing_status": "in_progress",
  "request_counts": {
    "canceled": 10,
    "errored": 30,
    "expired": 10,
    "processing": 100,
    "succeeded": 50
  },
  "results_url": "https://api.anthropic.com/v1/messages/batches/msgbatch_013Zva2CMHLNnXjNJJKqJ2EF/results",
  "type": "message_batch"
}
```

## Retrieve a Message Batch

`beta.messages.batches.retrieve(message_batch_id, **kwargs) -> BetaMessageBatch`

**get** `/v1/messages/batches/{message_batch_id}`

This endpoint is idempotent and can be used to poll for Message Batch completion. To access the results of a Message Batch, make a request to the `results_url` field in the response.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `message_batch_id: String`

  ID of the Message Batch.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageBatch`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `archived_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

  - `cancel_initiated_at: Time`

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

  - `created_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was created.

  - `ended_at: Time`

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

  - `expires_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

  - `processing_status: :in_progress | :canceling | :ended`

    Processing status of the Message Batch.

    - `:in_progress`

    - `:canceling`

    - `:ended`

  - `request_counts: BetaMessageBatchRequestCounts`

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as `processing` and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    - `canceled: Integer`

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

    - `errored: Integer`

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

    - `expired: Integer`

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

    - `processing: Integer`

      Number of requests in the Message Batch that are processing.

    - `succeeded: Integer`

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

  - `results_url: String`

    URL to a `.jsonl` file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

  - `type: :message_batch`

    Object type.

    For Message Batches, this is always `"message_batch"`.

    - `:message_batch`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message_batch = anthropic.beta.messages.batches.retrieve("message_batch_id")

puts(beta_message_batch)
```

#### Response

```json
{
  "id": "msgbatch_013Zva2CMHLNnXjNJJKqJ2EF",
  "archived_at": "2024-08-20T18:37:24.100435Z",
  "cancel_initiated_at": "2024-08-20T18:37:24.100435Z",
  "created_at": "2024-08-20T18:37:24.100435Z",
  "ended_at": "2024-08-20T18:37:24.100435Z",
  "expires_at": "2024-08-20T18:37:24.100435Z",
  "processing_status": "in_progress",
  "request_counts": {
    "canceled": 10,
    "errored": 30,
    "expired": 10,
    "processing": 100,
    "succeeded": 50
  },
  "results_url": "https://api.anthropic.com/v1/messages/batches/msgbatch_013Zva2CMHLNnXjNJJKqJ2EF/results",
  "type": "message_batch"
}
```

## List Message Batches

`beta.messages.batches.list(**kwargs) -> Page<BetaMessageBatch>`

**get** `/v1/messages/batches`

List all Message Batches within a Workspace. Most recently created batches are returned first.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `after_id: String`

  ID of the object to use as a cursor for pagination. When provided, returns the page of results immediately after this object.

- `before_id: String`

  ID of the object to use as a cursor for pagination. When provided, returns the page of results immediately before this object.

- `limit: Integer`

  Number of items to return per page.

  Defaults to `20`. Ranges from `1` to `1000`.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageBatch`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `archived_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

  - `cancel_initiated_at: Time`

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

  - `created_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was created.

  - `ended_at: Time`

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

  - `expires_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

  - `processing_status: :in_progress | :canceling | :ended`

    Processing status of the Message Batch.

    - `:in_progress`

    - `:canceling`

    - `:ended`

  - `request_counts: BetaMessageBatchRequestCounts`

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as `processing` and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    - `canceled: Integer`

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

    - `errored: Integer`

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

    - `expired: Integer`

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

    - `processing: Integer`

      Number of requests in the Message Batch that are processing.

    - `succeeded: Integer`

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

  - `results_url: String`

    URL to a `.jsonl` file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

  - `type: :message_batch`

    Object type.

    For Message Batches, this is always `"message_batch"`.

    - `:message_batch`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

page = anthropic.beta.messages.batches.list

puts(page)
```

#### Response

```json
{
  "data": [
    {
      "id": "msgbatch_013Zva2CMHLNnXjNJJKqJ2EF",
      "archived_at": "2024-08-20T18:37:24.100435Z",
      "cancel_initiated_at": "2024-08-20T18:37:24.100435Z",
      "created_at": "2024-08-20T18:37:24.100435Z",
      "ended_at": "2024-08-20T18:37:24.100435Z",
      "expires_at": "2024-08-20T18:37:24.100435Z",
      "processing_status": "in_progress",
      "request_counts": {
        "canceled": 10,
        "errored": 30,
        "expired": 10,
        "processing": 100,
        "succeeded": 50
      },
      "results_url": "https://api.anthropic.com/v1/messages/batches/msgbatch_013Zva2CMHLNnXjNJJKqJ2EF/results",
      "type": "message_batch"
    }
  ],
  "first_id": "first_id",
  "has_more": true,
  "last_id": "last_id"
}
```

## Cancel a Message Batch

`beta.messages.batches.cancel(message_batch_id, **kwargs) -> BetaMessageBatch`

**post** `/v1/messages/batches/{message_batch_id}/cancel`

Batches may be canceled any time before processing ends. Once cancellation is initiated, the batch enters a `canceling` state, at which time the system may complete any in-progress, non-interruptible requests before finalizing cancellation.

The number of canceled requests is specified in `request_counts`. To determine which requests were canceled, check the individual results within the batch. Note that cancellation may not result in any canceled requests if they were non-interruptible.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `message_batch_id: String`

  ID of the Message Batch.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageBatch`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `archived_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

  - `cancel_initiated_at: Time`

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

  - `created_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was created.

  - `ended_at: Time`

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

  - `expires_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

  - `processing_status: :in_progress | :canceling | :ended`

    Processing status of the Message Batch.

    - `:in_progress`

    - `:canceling`

    - `:ended`

  - `request_counts: BetaMessageBatchRequestCounts`

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as `processing` and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    - `canceled: Integer`

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

    - `errored: Integer`

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

    - `expired: Integer`

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

    - `processing: Integer`

      Number of requests in the Message Batch that are processing.

    - `succeeded: Integer`

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

  - `results_url: String`

    URL to a `.jsonl` file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

  - `type: :message_batch`

    Object type.

    For Message Batches, this is always `"message_batch"`.

    - `:message_batch`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message_batch = anthropic.beta.messages.batches.cancel("message_batch_id")

puts(beta_message_batch)
```

#### Response

```json
{
  "id": "msgbatch_013Zva2CMHLNnXjNJJKqJ2EF",
  "archived_at": "2024-08-20T18:37:24.100435Z",
  "cancel_initiated_at": "2024-08-20T18:37:24.100435Z",
  "created_at": "2024-08-20T18:37:24.100435Z",
  "ended_at": "2024-08-20T18:37:24.100435Z",
  "expires_at": "2024-08-20T18:37:24.100435Z",
  "processing_status": "in_progress",
  "request_counts": {
    "canceled": 10,
    "errored": 30,
    "expired": 10,
    "processing": 100,
    "succeeded": 50
  },
  "results_url": "https://api.anthropic.com/v1/messages/batches/msgbatch_013Zva2CMHLNnXjNJJKqJ2EF/results",
  "type": "message_batch"
}
```

## Delete a Message Batch

`beta.messages.batches.delete(message_batch_id, **kwargs) -> BetaDeletedMessageBatch`

**delete** `/v1/messages/batches/{message_batch_id}`

Delete a Message Batch.

Message Batches can only be deleted once they've finished processing. If you'd like to delete an in-progress batch, you must first cancel it.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `message_batch_id: String`

  ID of the Message Batch.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaDeletedMessageBatch`

  - `id: String`

    ID of the Message Batch.

  - `type: :message_batch_deleted`

    Deleted object type.

    For Message Batches, this is always `"message_batch_deleted"`.

    - `:message_batch_deleted`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_deleted_message_batch = anthropic.beta.messages.batches.delete("message_batch_id")

puts(beta_deleted_message_batch)
```

#### Response

```json
{
  "id": "msgbatch_013Zva2CMHLNnXjNJJKqJ2EF",
  "type": "message_batch_deleted"
}
```

## Retrieve Message Batch results

`beta.messages.batches.results(message_batch_id, **kwargs) -> BetaMessageBatchIndividualResponse`

**get** `/v1/messages/batches/{message_batch_id}/results`

Streams the results of a Message Batch as a `.jsonl` file.

Each line in the file is a JSON object containing the result of a single request in the Message Batch. Results are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

Learn more about the Message Batches API in our [user guide](https://docs.claude.com/en/docs/build-with-claude/batch-processing)

### Parameters

- `message_batch_id: String`

  ID of the Message Batch.

- `betas: Array[AnthropicBeta]`

  Optional header to specify the beta version(s) you want to use.

  - `String = String`

  - `AnthropicBeta = :"message-batches-2024-09-24" | :"prompt-caching-2024-07-31" | :"computer-use-2024-10-22" | 25 more`

    - `:"message-batches-2024-09-24"`

    - `:"prompt-caching-2024-07-31"`

    - `:"computer-use-2024-10-22"`

    - `:"computer-use-2025-01-24"`

    - `:"pdfs-2024-09-25"`

    - `:"token-counting-2024-11-01"`

    - `:"token-efficient-tools-2025-02-19"`

    - `:"output-128k-2025-02-19"`

    - `:"files-api-2025-04-14"`

    - `:"mcp-client-2025-04-04"`

    - `:"mcp-client-2025-11-20"`

    - `:"dev-full-thinking-2025-05-14"`

    - `:"interleaved-thinking-2025-05-14"`

    - `:"code-execution-2025-05-22"`

    - `:"extended-cache-ttl-2025-04-11"`

    - `:"context-1m-2025-08-07"`

    - `:"context-management-2025-06-27"`

    - `:"model-context-window-exceeded-2025-08-26"`

    - `:"skills-2025-10-02"`

    - `:"fast-mode-2026-02-01"`

    - `:"output-300k-2026-03-24"`

    - `:"user-profiles-2026-03-24"`

    - `:"advisor-tool-2026-03-01"`

    - `:"managed-agents-2026-04-01"`

    - `:"cache-diagnosis-2026-04-07"`

    - `:"thinking-token-count-2026-05-13"`

    - `:"server-side-fallback-2026-06-01"`

    - `:"fallback-credit-2026-06-01"`

### Returns

- `class BetaMessageBatchIndividualResponse`

  This is a single line in the response `.jsonl` file and does not represent the response as a whole.

  - `custom_id: String`

    Developer-provided ID created for each request in a Message Batch. Useful for matching results to requests, as results may be given out of request order.

    Must be unique for each request within the Message Batch.

  - `result: BetaMessageBatchResult`

    Processing result for this request.

    Contains a Message output if processing was successful, an error response if processing failed, or the reason why processing was not attempted, such as cancellation or expiration.

    - `class BetaMessageBatchSucceededResult`

      - `message: BetaMessage`

        - `id: String`

          Unique object identifier.

          The format and length of IDs may change over time.

        - `container: BetaContainer`

          Information about the container used in the request (for the code execution tool)

          - `id: String`

            Identifier for the container used in this request

          - `expires_at: Time`

            The time at which the container will expire.

          - `skills: Array[BetaSkill]`

            Skills loaded in the container

            - `skill_id: String`

              Skill ID

            - `type: :anthropic | :custom`

              Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

              - `:anthropic`

              - `:custom`

            - `version: String`

              Skill version or 'latest' for most recent version

        - `content: Array[BetaContentBlock]`

          Content generated by the model.

          This is an array of content blocks, each of which has a `type` that determines its shape.

          Example:

          ```json
          [{"type": "text", "text": "Hi, I'm Claude."}]
          ```

          If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

          For example, if the input `messages` were:

          ```json
          [
            {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
            {"role": "assistant", "content": "The best answer is ("}
          ]
          ```

          Then the response `content` might be:

          ```json
          [{"type": "text", "text": "B)"}]
          ```

          - `class BetaTextBlock`

            - `citations: Array[BetaTextCitation]`

              Citations supporting the text block.

              The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

              - `class BetaCitationCharLocation`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_char_index: Integer`

                - `file_id: String`

                - `start_char_index: Integer`

                - `type: :char_location`

                  - `:char_location`

              - `class BetaCitationPageLocation`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_page_number: Integer`

                - `file_id: String`

                - `start_page_number: Integer`

                - `type: :page_location`

                  - `:page_location`

              - `class BetaCitationContentBlockLocation`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `document_index: Integer`

                - `document_title: String`

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `file_id: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `type: :content_block_location`

                  - `:content_block_location`

              - `class BetaCitationsWebSearchResultLocation`

                - `cited_text: String`

                - `encrypted_index: String`

                - `title: String`

                - `type: :web_search_result_location`

                  - `:web_search_result_location`

                - `url: String`

              - `class BetaCitationSearchResultLocation`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `search_result_index: Integer`

                  0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from `document_index`; server-side web search results are not included in this count.

                - `source: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `title: String`

                - `type: :search_result_location`

                  - `:search_result_location`

            - `text: String`

            - `type: :text`

              - `:text`

          - `class BetaThinkingBlock`

            - `signature: String`

            - `thinking: String`

            - `type: :thinking`

              - `:thinking`

          - `class BetaRedactedThinkingBlock`

            - `data: String`

            - `type: :redacted_thinking`

              - `:redacted_thinking`

          - `class BetaToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

            - `type: :tool_use`

              - `:tool_use`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

                - `type: :direct`

                  - `:direct`

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

                - `tool_id: String`

                - `type: :code_execution_20250825`

                  - `:code_execution_20250825`

              - `class BetaServerToolCaller20260120`

                - `tool_id: String`

                - `type: :code_execution_20260120`

                  - `:code_execution_20260120`

          - `class BetaServerToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: :advisor | :web_search | :web_fetch | 5 more`

              - `:advisor`

              - `:web_search`

              - `:web_fetch`

              - `:code_execution`

              - `:bash_code_execution`

              - `:text_editor_code_execution`

              - `:tool_search_tool_regex`

              - `:tool_search_tool_bm25`

            - `type: :server_tool_use`

              - `:server_tool_use`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebSearchToolResultBlock`

            - `content: BetaWebSearchToolResultBlockContent`

              - `class BetaWebSearchToolResultError`

                - `error_code: BetaWebSearchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:max_uses_exceeded`

                  - `:too_many_requests`

                  - `:query_too_long`

                  - `:request_too_large`

                - `type: :web_search_tool_result_error`

                  - `:web_search_tool_result_error`

              - `UnionMember1 = Array[BetaWebSearchResultBlock]`

                - `encrypted_content: String`

                - `page_age: String`

                - `title: String`

                - `type: :web_search_result`

                  - `:web_search_result`

                - `url: String`

            - `tool_use_id: String`

            - `type: :web_search_tool_result`

              - `:web_search_tool_result`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebFetchToolResultBlock`

            - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

              - `class BetaWebFetchToolResultErrorBlock`

                - `error_code: BetaWebFetchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:url_too_long`

                  - `:url_not_allowed`

                  - `:url_not_in_prior_context`

                  - `:url_not_accessible`

                  - `:unsupported_content_type`

                  - `:too_many_requests`

                  - `:max_uses_exceeded`

                  - `:unavailable`

                - `type: :web_fetch_tool_result_error`

                  - `:web_fetch_tool_result_error`

              - `class BetaWebFetchBlock`

                - `content: BetaDocumentBlock`

                  - `citations: BetaCitationConfig`

                    Citation configuration for the document

                    - `enabled: bool`

                  - `source: BetaBase64PDFSource | BetaPlainTextSource`

                    - `class BetaBase64PDFSource`

                      - `data: String`

                      - `media_type: :"application/pdf"`

                        - `:"application/pdf"`

                      - `type: :base64`

                        - `:base64`

                    - `class BetaPlainTextSource`

                      - `data: String`

                      - `media_type: :"text/plain"`

                        - `:"text/plain"`

                      - `type: :text`

                        - `:text`

                  - `title: String`

                    The title of the document

                  - `type: :document`

                    - `:document`

                - `retrieved_at: String`

                  ISO 8601 timestamp when the content was retrieved

                - `type: :web_fetch_result`

                  - `:web_fetch_result`

                - `url: String`

                  Fetched content URL

            - `tool_use_id: String`

            - `type: :web_fetch_tool_result`

              - `:web_fetch_tool_result`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaAdvisorToolResultBlock`

            - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

              - `class BetaAdvisorToolResultError`

                - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

                  - `:max_uses_exceeded`

                  - `:prompt_too_long`

                  - `:too_many_requests`

                  - `:overloaded`

                  - `:unavailable`

                  - `:execution_time_exceeded`

                  - `:model_not_found`

                - `type: :advisor_tool_result_error`

                  - `:advisor_tool_result_error`

              - `class BetaAdvisorResultBlock`

                - `stop_reason: String`

                  The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

                - `text: String`

                - `type: :advisor_result`

                  - `:advisor_result`

              - `class BetaAdvisorRedactedResultBlock`

                - `encrypted_content: String`

                  Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

                - `stop_reason: String`

                  The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

                - `type: :advisor_redacted_result`

                  - `:advisor_redacted_result`

            - `tool_use_id: String`

            - `type: :advisor_tool_result`

              - `:advisor_tool_result`

          - `class BetaCodeExecutionToolResultBlock`

            - `content: BetaCodeExecutionToolResultBlockContent`

              Code execution result with encrypted stdout for PFC + web_search results.

              - `class BetaCodeExecutionToolResultError`

                - `error_code: BetaCodeExecutionToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `type: :code_execution_tool_result_error`

                  - `:code_execution_tool_result_error`

              - `class BetaCodeExecutionResultBlock`

                - `content: Array[BetaCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                    - `:code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :code_execution_result`

                  - `:code_execution_result`

              - `class BetaEncryptedCodeExecutionResultBlock`

                Code execution result with encrypted stdout for PFC + web_search results.

                - `content: Array[BetaCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                - `encrypted_stdout: String`

                - `return_code: Integer`

                - `stderr: String`

                - `type: :encrypted_code_execution_result`

                  - `:encrypted_code_execution_result`

            - `tool_use_id: String`

            - `type: :code_execution_tool_result`

              - `:code_execution_tool_result`

          - `class BetaBashCodeExecutionToolResultBlock`

            - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

              - `class BetaBashCodeExecutionToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:output_file_too_large`

                - `type: :bash_code_execution_tool_result_error`

                  - `:bash_code_execution_tool_result_error`

              - `class BetaBashCodeExecutionResultBlock`

                - `content: Array[BetaBashCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :bash_code_execution_output`

                    - `:bash_code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :bash_code_execution_result`

                  - `:bash_code_execution_result`

            - `tool_use_id: String`

            - `type: :bash_code_execution_tool_result`

              - `:bash_code_execution_tool_result`

          - `class BetaTextEditorCodeExecutionToolResultBlock`

            - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

              - `class BetaTextEditorCodeExecutionToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:file_not_found`

                - `error_message: String`

                - `type: :text_editor_code_execution_tool_result_error`

                  - `:text_editor_code_execution_tool_result_error`

              - `class BetaTextEditorCodeExecutionViewResultBlock`

                - `content: String`

                - `file_type: :text | :image | :pdf`

                  - `:text`

                  - `:image`

                  - `:pdf`

                - `num_lines: Integer`

                - `start_line: Integer`

                - `total_lines: Integer`

                - `type: :text_editor_code_execution_view_result`

                  - `:text_editor_code_execution_view_result`

              - `class BetaTextEditorCodeExecutionCreateResultBlock`

                - `is_file_update: bool`

                - `type: :text_editor_code_execution_create_result`

                  - `:text_editor_code_execution_create_result`

              - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

                - `lines: Array[String]`

                - `new_lines: Integer`

                - `new_start: Integer`

                - `old_lines: Integer`

                - `old_start: Integer`

                - `type: :text_editor_code_execution_str_replace_result`

                  - `:text_editor_code_execution_str_replace_result`

            - `tool_use_id: String`

            - `type: :text_editor_code_execution_tool_result`

              - `:text_editor_code_execution_tool_result`

          - `class BetaToolSearchToolResultBlock`

            - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

              - `class BetaToolSearchToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `error_message: String`

                - `type: :tool_search_tool_result_error`

                  - `:tool_search_tool_result_error`

              - `class BetaToolSearchToolSearchResultBlock`

                - `tool_references: Array[BetaToolReferenceBlock]`

                  - `tool_name: String`

                  - `type: :tool_reference`

                    - `:tool_reference`

                - `type: :tool_search_tool_search_result`

                  - `:tool_search_tool_search_result`

            - `tool_use_id: String`

            - `type: :tool_search_tool_result`

              - `:tool_search_tool_result`

          - `class BetaMCPToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

              The name of the MCP tool

            - `server_name: String`

              The name of the MCP server

            - `type: :mcp_tool_use`

              - `:mcp_tool_use`

          - `class BetaMCPToolResultBlock`

            - `content: String | Array[BetaTextBlock]`

              - `String = String`

              - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

                - `citations: Array[BetaTextCitation]`

                  Citations supporting the text block.

                  The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

                - `text: String`

                - `type: :text`

            - `is_error: bool`

            - `tool_use_id: String`

            - `type: :mcp_tool_result`

              - `:mcp_tool_result`

          - `class BetaContainerUploadBlock`

            Response model for a file uploaded to the container.

            - `file_id: String`

            - `type: :container_upload`

              - `:container_upload`

          - `class BetaCompactionBlock`

            A compaction block returned when autocompact is triggered.

            When content is None, it indicates the compaction failed to produce a valid
            summary (e.g., malformed output from the model). Clients may round-trip
            compaction blocks with null content; the server treats them as no-ops.

            - `content: String`

              Summary of compacted content, or null if compaction failed

            - `encrypted_content: String`

              Opaque metadata from prior compaction, to be round-tripped verbatim

            - `type: :compaction`

              - `:compaction`

          - `class BetaFallbackBlock`

            Marks the point in `content` where one model's output gives way to the next.

            One block appears per hop where a preceding model actually ran this turn and
            declined. A turn routed directly by the sticky decision has no such boundary
            and carries no block — the signal for whether a fallback model served the
            response is the presence of a `fallback_message` entry in
            `usage.iterations`, not this block.

            The block is treated like a server-tool content block for streaming: it
            arrives via the standard `content_block_start` / `content_block_stop`
            pair and carries no deltas.

            - `from: BetaFallbackInfo`

              The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

                  The model that will complete your prompt.

                  See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                  - `:"claude-fable-5"`

                    Next generation of intelligence for the hardest knowledge work and coding problems

                  - `:"claude-mythos-5"`

                    Most capable model for cybersecurity and biology research

                  - `:"claude-opus-4-8"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-opus-4-7"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-mythos-preview"`

                    New class of intelligence, strongest in coding and cybersecurity

                  - `:"claude-opus-4-6"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-sonnet-4-6"`

                    Best combination of speed and intelligence

                  - `:"claude-haiku-4-5"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-haiku-4-5-20251001"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-opus-4-5"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-opus-4-5-20251101"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-sonnet-4-5"`

                    High-performance model for agents and coding

                  - `:"claude-sonnet-4-5-20250929"`

                    High-performance model for agents and coding

                  - `:"claude-opus-4-1"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-1-20250805"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-0"`

                    Powerful model for complex tasks

                  - `:"claude-opus-4-20250514"`

                    Powerful model for complex tasks

                  - `:"claude-sonnet-4-0"`

                    High-performance model with extended thinking

                  - `:"claude-sonnet-4-20250514"`

                    High-performance model with extended thinking

                  - `:"claude-3-haiku-20240307"`

                    Fast and cost-effective model

                - `String = String`

            - `to: BetaFallbackInfo`

              The fallback model producing the content that follows this block. Its `model` is always the canonical id.

            - `type: :fallback`

              - `:fallback`

        - `context_management: BetaContextManagementResponse`

          Context management response.

          Information about context management strategies applied during the request.

          - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

            List of context management edits that were applied.

            - `class BetaClearToolUses20250919EditResponse`

              - `cleared_input_tokens: Integer`

                Number of input tokens cleared by this edit.

              - `cleared_tool_uses: Integer`

                Number of tool uses that were cleared.

              - `type: :clear_tool_uses_20250919`

                The type of context management edit applied.

                - `:clear_tool_uses_20250919`

            - `class BetaClearThinking20251015EditResponse`

              - `cleared_input_tokens: Integer`

                Number of input tokens cleared by this edit.

              - `cleared_thinking_turns: Integer`

                Number of thinking turns that were cleared.

              - `type: :clear_thinking_20251015`

                The type of context management edit applied.

                - `:clear_thinking_20251015`

        - `diagnostics: BetaDiagnostics`

          Response envelope for request-level diagnostics. Present (possibly
          null) whenever the caller supplied `diagnostics` on the request.

          - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

            Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

            - `class BetaCacheMissModelChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :model_changed`

                - `:model_changed`

            - `class BetaCacheMissSystemChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :system_changed`

                - `:system_changed`

            - `class BetaCacheMissToolsChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :tools_changed`

                - `:tools_changed`

            - `class BetaCacheMissMessagesChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :messages_changed`

                - `:messages_changed`

            - `class BetaCacheMissPreviousMessageNotFound`

              - `type: :previous_message_not_found`

                - `:previous_message_not_found`

            - `class BetaCacheMissUnavailable`

              - `type: :unavailable`

                - `:unavailable`

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `role: :assistant`

          Conversational role of the generated message.

          This will always be `"assistant"`.

          - `:assistant`

        - `stop_details: BetaRefusalStopDetails`

          Structured information about a refusal.

          - `category: :cyber | :bio | :reasoning_extraction`

            The policy category that triggered the refusal.

            `null` when the refusal doesn't map to a named category.

            - `:cyber`

            - `:bio`

            - `:reasoning_extraction`

          - `explanation: String`

            Human-readable explanation of the refusal.

            This text is not guaranteed to be stable. `null` when no explanation is available for the category.

          - `fallback_credit_token: String`

            Opaque code that refunds the cache-miss cost when retrying this refused
            request on the fallback model. Pass it as `fallback_credit_token` on the
            retry request. Expires 5 minutes after the refusal.

            The retry is sent either with the same request body (`system`, `messages`,
            `tools`, and other render-shaping fields), or with the same body plus one
            appended `assistant` message whose content is the partial text (with any
            trailing whitespace stripped from the final text block) and paired
            server-tool blocks from this refusal — which also authorizes that
            appended turn as an assistant-prefill continuation on models that otherwise
            disallow prefill. A token minted mid-server-tool-loop whose partial content
            was continuable may only be redeemed the second way — if a same-body retry
            is rejected with a 400 saying the token must be redeemed by continuing the
            partial response, retry the second way instead. Either way: same workspace,
            same platform; a mismatch is a 400. Resending a token for an already-warm
            prefix is permitted but yields no additional credit.

            `null` when the refused model isn't eligible for a fallback credit.

          - `fallback_has_prefill_claim: bool`

            Whether the accompanying `fallback_credit_token` may be redeemed with the
            appended-assistant retry form. Only set when `fallback_credit_token` is
            present.

            `true`: retry by resending the same request body plus one appended
            `assistant` message whose content is this response's `content` with any
            trailing whitespace stripped from the final text block and unpaired
            `tool_use` blocks omitted (the same appended-turn shape described on
            `fallback_credit_token`), with the token attached. `false`: retry by
            resending the original request body unchanged, with the token attached —
            the appended-assistant form is not available for this refusal (no
            continuable partial content, or the request uses `output_format` or a
            `tool_choice` that forces tool use). One exception: when the request used
            `output_format` or a forced `tool_choice` and the refusal arrived after
            server tools (including MCP connector tools) had already executed, the
            token may not be redeemable by either retry form; if the exact-body retry
            is then rejected with a 400 saying the token must be redeemed by
            continuing the partial response, discard the token and retry without it.

            Advisory: if an appended-assistant retry is rejected with a 400 despite
            `true`, fall back to resending the original request body with the token.

          - `recommended_model: String`

            The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

          - `type: :refusal`

            - `:refusal`

        - `stop_reason: BetaStopReason`

          The reason that we stopped.

          This may be one the following values:

          * `"end_turn"`: the model reached a natural stopping point
          * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
          * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
          * `"tool_use"`: the model invoked one or more tools
          * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
          * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

          In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

          - `:end_turn`

          - `:max_tokens`

          - `:stop_sequence`

          - `:tool_use`

          - `:pause_turn`

          - `:compaction`

          - `:refusal`

          - `:model_context_window_exceeded`

        - `stop_sequence: String`

          Which custom stop sequence was generated, if any.

          This value will be a non-null string if one of your custom stop sequences was generated.

        - `type: :message`

          Object type.

          For Messages, this is always `"message"`.

          - `:message`

        - `usage: BetaUsage`

          Billing and rate-limit usage.

          Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

          Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

          For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

          Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

            - `ephemeral_1h_input_tokens: Integer`

              The number of input tokens used to create the 1 hour cache entry.

            - `ephemeral_5m_input_tokens: Integer`

              The number of input tokens used to create the 5 minute cache entry.

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `inference_geo: String`

            The geographic region where inference was performed for this request.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `iterations: BetaIterationsUsage`

            Per-iteration token usage breakdown.

            Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

            - Determine which iterations exceeded long context thresholds (>=200k tokens)
            - Calculate the true context window size from the last iteration
            - Understand token accumulation across server-side tool use loops

            - `class BetaMessageIterationUsage`

              Token usage for a sampling iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :message`

                Usage for a sampling iteration

                - `:message`

            - `class BetaCompactionIterationUsage`

              Token usage for a compaction iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :compaction`

                Usage for a compaction iteration

                - `:compaction`

            - `class BetaAdvisorMessageIterationUsage`

              Token usage for an advisor sub-inference iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :advisor_message`

                Usage for an advisor sub-inference iteration

                - `:advisor_message`

            - `class BetaFallbackMessageIterationUsage`

              Token usage for the fallback-model attempt of a server-side fallback request.

              Produced in place of a `message` entry for whichever hop served the
              response. A declined hop produces the existing `message` entry. Whether
              a fallback model served the response is signalled by the presence of this
              entry in `usage.iterations`.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :fallback_message`

                Usage for the fallback-model attempt that served the response

                - `:fallback_message`

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `output_tokens_details: BetaOutputTokensDetails`

            Breakdown of output tokens by category.

            `output_tokens` remains the inclusive, authoritative total used for billing.
            This object provides a read-only decomposition for observability — for example,
            how many of the billed output tokens were spent on internal reasoning that may
            have been summarized before being returned to you.

            - `thinking_tokens: Integer`

              Number of output tokens the model generated as internal reasoning, including
              the thinking-block delimiter tokens.

              Reflects the raw reasoning the model produced, not the (possibly shorter)
              summarized thinking text returned in the response body. Computed by
              re-tokenizing the raw reasoning text, so it may differ from the model's exact
              generation count by a small number of tokens. Always ≤ `output_tokens`;
              `output_tokens - thinking_tokens` approximates the non-reasoning output.

          - `server_tool_use: BetaServerToolUsage`

            The number of server tool requests.

            - `web_fetch_requests: Integer`

              The number of web fetch tool requests.

            - `web_search_requests: Integer`

              The number of web search tool requests.

          - `service_tier: :standard | :priority | :batch`

            If the request used the priority, standard, or batch tier.

            - `:standard`

            - `:priority`

            - `:batch`

          - `speed: :standard | :fast`

            The inference speed mode used for this request.

            - `:standard`

            - `:fast`

      - `type: :succeeded`

        - `:succeeded`

    - `class BetaMessageBatchErroredResult`

      - `error: BetaErrorResponse`

        - `error: BetaError`

          - `class BetaInvalidRequestError`

            - `message: String`

            - `type: :invalid_request_error`

              - `:invalid_request_error`

          - `class BetaAuthenticationError`

            - `message: String`

            - `type: :authentication_error`

              - `:authentication_error`

          - `class BetaBillingError`

            - `message: String`

            - `type: :billing_error`

              - `:billing_error`

          - `class BetaPermissionError`

            - `message: String`

            - `type: :permission_error`

              - `:permission_error`

          - `class BetaNotFoundError`

            - `message: String`

            - `type: :not_found_error`

              - `:not_found_error`

          - `class BetaRateLimitError`

            - `message: String`

            - `type: :rate_limit_error`

              - `:rate_limit_error`

          - `class BetaGatewayTimeoutError`

            - `message: String`

            - `type: :timeout_error`

              - `:timeout_error`

          - `class BetaAPIError`

            - `message: String`

            - `type: :api_error`

              - `:api_error`

          - `class BetaOverloadedError`

            - `message: String`

            - `type: :overloaded_error`

              - `:overloaded_error`

        - `request_id: String`

        - `type: :error`

          - `:error`

      - `type: :errored`

        - `:errored`

    - `class BetaMessageBatchCanceledResult`

      - `type: :canceled`

        - `:canceled`

    - `class BetaMessageBatchExpiredResult`

      - `type: :expired`

        - `:expired`

### Example

```ruby
require "anthropic"

anthropic = Anthropic::Client.new(api_key: "my-anthropic-api-key")

beta_message_batch_individual_response = anthropic.beta.messages.batches.results("message_batch_id")

puts(beta_message_batch_individual_response)
```

## Domain Types

### Beta Deleted Message Batch

- `class BetaDeletedMessageBatch`

  - `id: String`

    ID of the Message Batch.

  - `type: :message_batch_deleted`

    Deleted object type.

    For Message Batches, this is always `"message_batch_deleted"`.

    - `:message_batch_deleted`

### Beta Message Batch

- `class BetaMessageBatch`

  - `id: String`

    Unique object identifier.

    The format and length of IDs may change over time.

  - `archived_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

  - `cancel_initiated_at: Time`

    RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

  - `created_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch was created.

  - `ended_at: Time`

    RFC 3339 datetime string representing the time at which processing for the Message Batch ended. Specified only once processing ends.

    Processing ends when every request in a Message Batch has either succeeded, errored, canceled, or expired.

  - `expires_at: Time`

    RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

  - `processing_status: :in_progress | :canceling | :ended`

    Processing status of the Message Batch.

    - `:in_progress`

    - `:canceling`

    - `:ended`

  - `request_counts: BetaMessageBatchRequestCounts`

    Tallies requests within the Message Batch, categorized by their status.

    Requests start as `processing` and move to one of the other statuses only once processing of the entire batch ends. The sum of all values always matches the total number of requests in the batch.

    - `canceled: Integer`

      Number of requests in the Message Batch that have been canceled.

      This is zero until processing of the entire Message Batch has ended.

    - `errored: Integer`

      Number of requests in the Message Batch that encountered an error.

      This is zero until processing of the entire Message Batch has ended.

    - `expired: Integer`

      Number of requests in the Message Batch that have expired.

      This is zero until processing of the entire Message Batch has ended.

    - `processing: Integer`

      Number of requests in the Message Batch that are processing.

    - `succeeded: Integer`

      Number of requests in the Message Batch that have completed successfully.

      This is zero until processing of the entire Message Batch has ended.

  - `results_url: String`

    URL to a `.jsonl` file containing the results of the Message Batch requests. Specified only once processing ends.

    Results in the file are not guaranteed to be in the same order as requests. Use the `custom_id` field to match results to requests.

  - `type: :message_batch`

    Object type.

    For Message Batches, this is always `"message_batch"`.

    - `:message_batch`

### Beta Message Batch Canceled Result

- `class BetaMessageBatchCanceledResult`

  - `type: :canceled`

    - `:canceled`

### Beta Message Batch Errored Result

- `class BetaMessageBatchErroredResult`

  - `error: BetaErrorResponse`

    - `error: BetaError`

      - `class BetaInvalidRequestError`

        - `message: String`

        - `type: :invalid_request_error`

          - `:invalid_request_error`

      - `class BetaAuthenticationError`

        - `message: String`

        - `type: :authentication_error`

          - `:authentication_error`

      - `class BetaBillingError`

        - `message: String`

        - `type: :billing_error`

          - `:billing_error`

      - `class BetaPermissionError`

        - `message: String`

        - `type: :permission_error`

          - `:permission_error`

      - `class BetaNotFoundError`

        - `message: String`

        - `type: :not_found_error`

          - `:not_found_error`

      - `class BetaRateLimitError`

        - `message: String`

        - `type: :rate_limit_error`

          - `:rate_limit_error`

      - `class BetaGatewayTimeoutError`

        - `message: String`

        - `type: :timeout_error`

          - `:timeout_error`

      - `class BetaAPIError`

        - `message: String`

        - `type: :api_error`

          - `:api_error`

      - `class BetaOverloadedError`

        - `message: String`

        - `type: :overloaded_error`

          - `:overloaded_error`

    - `request_id: String`

    - `type: :error`

      - `:error`

  - `type: :errored`

    - `:errored`

### Beta Message Batch Expired Result

- `class BetaMessageBatchExpiredResult`

  - `type: :expired`

    - `:expired`

### Beta Message Batch Individual Response

- `class BetaMessageBatchIndividualResponse`

  This is a single line in the response `.jsonl` file and does not represent the response as a whole.

  - `custom_id: String`

    Developer-provided ID created for each request in a Message Batch. Useful for matching results to requests, as results may be given out of request order.

    Must be unique for each request within the Message Batch.

  - `result: BetaMessageBatchResult`

    Processing result for this request.

    Contains a Message output if processing was successful, an error response if processing failed, or the reason why processing was not attempted, such as cancellation or expiration.

    - `class BetaMessageBatchSucceededResult`

      - `message: BetaMessage`

        - `id: String`

          Unique object identifier.

          The format and length of IDs may change over time.

        - `container: BetaContainer`

          Information about the container used in the request (for the code execution tool)

          - `id: String`

            Identifier for the container used in this request

          - `expires_at: Time`

            The time at which the container will expire.

          - `skills: Array[BetaSkill]`

            Skills loaded in the container

            - `skill_id: String`

              Skill ID

            - `type: :anthropic | :custom`

              Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

              - `:anthropic`

              - `:custom`

            - `version: String`

              Skill version or 'latest' for most recent version

        - `content: Array[BetaContentBlock]`

          Content generated by the model.

          This is an array of content blocks, each of which has a `type` that determines its shape.

          Example:

          ```json
          [{"type": "text", "text": "Hi, I'm Claude."}]
          ```

          If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

          For example, if the input `messages` were:

          ```json
          [
            {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
            {"role": "assistant", "content": "The best answer is ("}
          ]
          ```

          Then the response `content` might be:

          ```json
          [{"type": "text", "text": "B)"}]
          ```

          - `class BetaTextBlock`

            - `citations: Array[BetaTextCitation]`

              Citations supporting the text block.

              The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

              - `class BetaCitationCharLocation`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_char_index: Integer`

                - `file_id: String`

                - `start_char_index: Integer`

                - `type: :char_location`

                  - `:char_location`

              - `class BetaCitationPageLocation`

                - `cited_text: String`

                - `document_index: Integer`

                - `document_title: String`

                - `end_page_number: Integer`

                - `file_id: String`

                - `start_page_number: Integer`

                - `type: :page_location`

                  - `:page_location`

              - `class BetaCitationContentBlockLocation`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `document_index: Integer`

                - `document_title: String`

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `file_id: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `type: :content_block_location`

                  - `:content_block_location`

              - `class BetaCitationsWebSearchResultLocation`

                - `cited_text: String`

                - `encrypted_index: String`

                - `title: String`

                - `type: :web_search_result_location`

                  - `:web_search_result_location`

                - `url: String`

              - `class BetaCitationSearchResultLocation`

                - `cited_text: String`

                  The full text of the cited block range, concatenated.

                  Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

                - `end_block_index: Integer`

                  Exclusive 0-based end index of the cited block range in the source's `content` array.

                  Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

                - `search_result_index: Integer`

                  0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                  Counted separately from `document_index`; server-side web search results are not included in this count.

                - `source: String`

                - `start_block_index: Integer`

                  0-based index of the first cited block in the source's `content` array.

                - `title: String`

                - `type: :search_result_location`

                  - `:search_result_location`

            - `text: String`

            - `type: :text`

              - `:text`

          - `class BetaThinkingBlock`

            - `signature: String`

            - `thinking: String`

            - `type: :thinking`

              - `:thinking`

          - `class BetaRedactedThinkingBlock`

            - `data: String`

            - `type: :redacted_thinking`

              - `:redacted_thinking`

          - `class BetaToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

            - `type: :tool_use`

              - `:tool_use`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

                - `type: :direct`

                  - `:direct`

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

                - `tool_id: String`

                - `type: :code_execution_20250825`

                  - `:code_execution_20250825`

              - `class BetaServerToolCaller20260120`

                - `tool_id: String`

                - `type: :code_execution_20260120`

                  - `:code_execution_20260120`

          - `class BetaServerToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: :advisor | :web_search | :web_fetch | 5 more`

              - `:advisor`

              - `:web_search`

              - `:web_fetch`

              - `:code_execution`

              - `:bash_code_execution`

              - `:text_editor_code_execution`

              - `:tool_search_tool_regex`

              - `:tool_search_tool_bm25`

            - `type: :server_tool_use`

              - `:server_tool_use`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebSearchToolResultBlock`

            - `content: BetaWebSearchToolResultBlockContent`

              - `class BetaWebSearchToolResultError`

                - `error_code: BetaWebSearchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:max_uses_exceeded`

                  - `:too_many_requests`

                  - `:query_too_long`

                  - `:request_too_large`

                - `type: :web_search_tool_result_error`

                  - `:web_search_tool_result_error`

              - `UnionMember1 = Array[BetaWebSearchResultBlock]`

                - `encrypted_content: String`

                - `page_age: String`

                - `title: String`

                - `type: :web_search_result`

                  - `:web_search_result`

                - `url: String`

            - `tool_use_id: String`

            - `type: :web_search_tool_result`

              - `:web_search_tool_result`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaWebFetchToolResultBlock`

            - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

              - `class BetaWebFetchToolResultErrorBlock`

                - `error_code: BetaWebFetchToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:url_too_long`

                  - `:url_not_allowed`

                  - `:url_not_in_prior_context`

                  - `:url_not_accessible`

                  - `:unsupported_content_type`

                  - `:too_many_requests`

                  - `:max_uses_exceeded`

                  - `:unavailable`

                - `type: :web_fetch_tool_result_error`

                  - `:web_fetch_tool_result_error`

              - `class BetaWebFetchBlock`

                - `content: BetaDocumentBlock`

                  - `citations: BetaCitationConfig`

                    Citation configuration for the document

                    - `enabled: bool`

                  - `source: BetaBase64PDFSource | BetaPlainTextSource`

                    - `class BetaBase64PDFSource`

                      - `data: String`

                      - `media_type: :"application/pdf"`

                        - `:"application/pdf"`

                      - `type: :base64`

                        - `:base64`

                    - `class BetaPlainTextSource`

                      - `data: String`

                      - `media_type: :"text/plain"`

                        - `:"text/plain"`

                      - `type: :text`

                        - `:text`

                  - `title: String`

                    The title of the document

                  - `type: :document`

                    - `:document`

                - `retrieved_at: String`

                  ISO 8601 timestamp when the content was retrieved

                - `type: :web_fetch_result`

                  - `:web_fetch_result`

                - `url: String`

                  Fetched content URL

            - `tool_use_id: String`

            - `type: :web_fetch_tool_result`

              - `:web_fetch_tool_result`

            - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

              Tool invocation directly from the model.

              - `class BetaDirectCaller`

                Tool invocation directly from the model.

              - `class BetaServerToolCaller`

                Tool invocation generated by a server-side tool.

              - `class BetaServerToolCaller20260120`

          - `class BetaAdvisorToolResultBlock`

            - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

              - `class BetaAdvisorToolResultError`

                - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

                  - `:max_uses_exceeded`

                  - `:prompt_too_long`

                  - `:too_many_requests`

                  - `:overloaded`

                  - `:unavailable`

                  - `:execution_time_exceeded`

                  - `:model_not_found`

                - `type: :advisor_tool_result_error`

                  - `:advisor_tool_result_error`

              - `class BetaAdvisorResultBlock`

                - `stop_reason: String`

                  The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

                - `text: String`

                - `type: :advisor_result`

                  - `:advisor_result`

              - `class BetaAdvisorRedactedResultBlock`

                - `encrypted_content: String`

                  Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

                - `stop_reason: String`

                  The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

                - `type: :advisor_redacted_result`

                  - `:advisor_redacted_result`

            - `tool_use_id: String`

            - `type: :advisor_tool_result`

              - `:advisor_tool_result`

          - `class BetaCodeExecutionToolResultBlock`

            - `content: BetaCodeExecutionToolResultBlockContent`

              Code execution result with encrypted stdout for PFC + web_search results.

              - `class BetaCodeExecutionToolResultError`

                - `error_code: BetaCodeExecutionToolResultErrorCode`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `type: :code_execution_tool_result_error`

                  - `:code_execution_tool_result_error`

              - `class BetaCodeExecutionResultBlock`

                - `content: Array[BetaCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                    - `:code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :code_execution_result`

                  - `:code_execution_result`

              - `class BetaEncryptedCodeExecutionResultBlock`

                Code execution result with encrypted stdout for PFC + web_search results.

                - `content: Array[BetaCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :code_execution_output`

                - `encrypted_stdout: String`

                - `return_code: Integer`

                - `stderr: String`

                - `type: :encrypted_code_execution_result`

                  - `:encrypted_code_execution_result`

            - `tool_use_id: String`

            - `type: :code_execution_tool_result`

              - `:code_execution_tool_result`

          - `class BetaBashCodeExecutionToolResultBlock`

            - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

              - `class BetaBashCodeExecutionToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:output_file_too_large`

                - `type: :bash_code_execution_tool_result_error`

                  - `:bash_code_execution_tool_result_error`

              - `class BetaBashCodeExecutionResultBlock`

                - `content: Array[BetaBashCodeExecutionOutputBlock]`

                  - `file_id: String`

                  - `type: :bash_code_execution_output`

                    - `:bash_code_execution_output`

                - `return_code: Integer`

                - `stderr: String`

                - `stdout: String`

                - `type: :bash_code_execution_result`

                  - `:bash_code_execution_result`

            - `tool_use_id: String`

            - `type: :bash_code_execution_tool_result`

              - `:bash_code_execution_tool_result`

          - `class BetaTextEditorCodeExecutionToolResultBlock`

            - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

              - `class BetaTextEditorCodeExecutionToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                  - `:file_not_found`

                - `error_message: String`

                - `type: :text_editor_code_execution_tool_result_error`

                  - `:text_editor_code_execution_tool_result_error`

              - `class BetaTextEditorCodeExecutionViewResultBlock`

                - `content: String`

                - `file_type: :text | :image | :pdf`

                  - `:text`

                  - `:image`

                  - `:pdf`

                - `num_lines: Integer`

                - `start_line: Integer`

                - `total_lines: Integer`

                - `type: :text_editor_code_execution_view_result`

                  - `:text_editor_code_execution_view_result`

              - `class BetaTextEditorCodeExecutionCreateResultBlock`

                - `is_file_update: bool`

                - `type: :text_editor_code_execution_create_result`

                  - `:text_editor_code_execution_create_result`

              - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

                - `lines: Array[String]`

                - `new_lines: Integer`

                - `new_start: Integer`

                - `old_lines: Integer`

                - `old_start: Integer`

                - `type: :text_editor_code_execution_str_replace_result`

                  - `:text_editor_code_execution_str_replace_result`

            - `tool_use_id: String`

            - `type: :text_editor_code_execution_tool_result`

              - `:text_editor_code_execution_tool_result`

          - `class BetaToolSearchToolResultBlock`

            - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

              - `class BetaToolSearchToolResultError`

                - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

                  - `:invalid_tool_input`

                  - `:unavailable`

                  - `:too_many_requests`

                  - `:execution_time_exceeded`

                - `error_message: String`

                - `type: :tool_search_tool_result_error`

                  - `:tool_search_tool_result_error`

              - `class BetaToolSearchToolSearchResultBlock`

                - `tool_references: Array[BetaToolReferenceBlock]`

                  - `tool_name: String`

                  - `type: :tool_reference`

                    - `:tool_reference`

                - `type: :tool_search_tool_search_result`

                  - `:tool_search_tool_search_result`

            - `tool_use_id: String`

            - `type: :tool_search_tool_result`

              - `:tool_search_tool_result`

          - `class BetaMCPToolUseBlock`

            - `id: String`

            - `input: Hash[Symbol, untyped]`

            - `name: String`

              The name of the MCP tool

            - `server_name: String`

              The name of the MCP server

            - `type: :mcp_tool_use`

              - `:mcp_tool_use`

          - `class BetaMCPToolResultBlock`

            - `content: String | Array[BetaTextBlock]`

              - `String = String`

              - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

                - `citations: Array[BetaTextCitation]`

                  Citations supporting the text block.

                  The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

                - `text: String`

                - `type: :text`

            - `is_error: bool`

            - `tool_use_id: String`

            - `type: :mcp_tool_result`

              - `:mcp_tool_result`

          - `class BetaContainerUploadBlock`

            Response model for a file uploaded to the container.

            - `file_id: String`

            - `type: :container_upload`

              - `:container_upload`

          - `class BetaCompactionBlock`

            A compaction block returned when autocompact is triggered.

            When content is None, it indicates the compaction failed to produce a valid
            summary (e.g., malformed output from the model). Clients may round-trip
            compaction blocks with null content; the server treats them as no-ops.

            - `content: String`

              Summary of compacted content, or null if compaction failed

            - `encrypted_content: String`

              Opaque metadata from prior compaction, to be round-tripped verbatim

            - `type: :compaction`

              - `:compaction`

          - `class BetaFallbackBlock`

            Marks the point in `content` where one model's output gives way to the next.

            One block appears per hop where a preceding model actually ran this turn and
            declined. A turn routed directly by the sticky decision has no such boundary
            and carries no block — the signal for whether a fallback model served the
            response is the presence of a `fallback_message` entry in
            `usage.iterations`, not this block.

            The block is treated like a server-tool content block for streaming: it
            arrives via the standard `content_block_start` / `content_block_stop`
            pair and carries no deltas.

            - `from: BetaFallbackInfo`

              The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

                  The model that will complete your prompt.

                  See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                  - `:"claude-fable-5"`

                    Next generation of intelligence for the hardest knowledge work and coding problems

                  - `:"claude-mythos-5"`

                    Most capable model for cybersecurity and biology research

                  - `:"claude-opus-4-8"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-opus-4-7"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-mythos-preview"`

                    New class of intelligence, strongest in coding and cybersecurity

                  - `:"claude-opus-4-6"`

                    Frontier intelligence for long-running agents and coding

                  - `:"claude-sonnet-4-6"`

                    Best combination of speed and intelligence

                  - `:"claude-haiku-4-5"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-haiku-4-5-20251001"`

                    Fastest model with near-frontier intelligence

                  - `:"claude-opus-4-5"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-opus-4-5-20251101"`

                    Premium model combining maximum intelligence with practical performance

                  - `:"claude-sonnet-4-5"`

                    High-performance model for agents and coding

                  - `:"claude-sonnet-4-5-20250929"`

                    High-performance model for agents and coding

                  - `:"claude-opus-4-1"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-1-20250805"`

                    Exceptional model for specialized complex tasks

                  - `:"claude-opus-4-0"`

                    Powerful model for complex tasks

                  - `:"claude-opus-4-20250514"`

                    Powerful model for complex tasks

                  - `:"claude-sonnet-4-0"`

                    High-performance model with extended thinking

                  - `:"claude-sonnet-4-20250514"`

                    High-performance model with extended thinking

                  - `:"claude-3-haiku-20240307"`

                    Fast and cost-effective model

                - `String = String`

            - `to: BetaFallbackInfo`

              The fallback model producing the content that follows this block. Its `model` is always the canonical id.

            - `type: :fallback`

              - `:fallback`

        - `context_management: BetaContextManagementResponse`

          Context management response.

          Information about context management strategies applied during the request.

          - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

            List of context management edits that were applied.

            - `class BetaClearToolUses20250919EditResponse`

              - `cleared_input_tokens: Integer`

                Number of input tokens cleared by this edit.

              - `cleared_tool_uses: Integer`

                Number of tool uses that were cleared.

              - `type: :clear_tool_uses_20250919`

                The type of context management edit applied.

                - `:clear_tool_uses_20250919`

            - `class BetaClearThinking20251015EditResponse`

              - `cleared_input_tokens: Integer`

                Number of input tokens cleared by this edit.

              - `cleared_thinking_turns: Integer`

                Number of thinking turns that were cleared.

              - `type: :clear_thinking_20251015`

                The type of context management edit applied.

                - `:clear_thinking_20251015`

        - `diagnostics: BetaDiagnostics`

          Response envelope for request-level diagnostics. Present (possibly
          null) whenever the caller supplied `diagnostics` on the request.

          - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

            Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

            - `class BetaCacheMissModelChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :model_changed`

                - `:model_changed`

            - `class BetaCacheMissSystemChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :system_changed`

                - `:system_changed`

            - `class BetaCacheMissToolsChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :tools_changed`

                - `:tools_changed`

            - `class BetaCacheMissMessagesChanged`

              - `cache_missed_input_tokens: Integer`

                Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

              - `type: :messages_changed`

                - `:messages_changed`

            - `class BetaCacheMissPreviousMessageNotFound`

              - `type: :previous_message_not_found`

                - `:previous_message_not_found`

            - `class BetaCacheMissUnavailable`

              - `type: :unavailable`

                - `:unavailable`

        - `model: Model`

          The model that will complete your prompt.

          See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

        - `role: :assistant`

          Conversational role of the generated message.

          This will always be `"assistant"`.

          - `:assistant`

        - `stop_details: BetaRefusalStopDetails`

          Structured information about a refusal.

          - `category: :cyber | :bio | :reasoning_extraction`

            The policy category that triggered the refusal.

            `null` when the refusal doesn't map to a named category.

            - `:cyber`

            - `:bio`

            - `:reasoning_extraction`

          - `explanation: String`

            Human-readable explanation of the refusal.

            This text is not guaranteed to be stable. `null` when no explanation is available for the category.

          - `fallback_credit_token: String`

            Opaque code that refunds the cache-miss cost when retrying this refused
            request on the fallback model. Pass it as `fallback_credit_token` on the
            retry request. Expires 5 minutes after the refusal.

            The retry is sent either with the same request body (`system`, `messages`,
            `tools`, and other render-shaping fields), or with the same body plus one
            appended `assistant` message whose content is the partial text (with any
            trailing whitespace stripped from the final text block) and paired
            server-tool blocks from this refusal — which also authorizes that
            appended turn as an assistant-prefill continuation on models that otherwise
            disallow prefill. A token minted mid-server-tool-loop whose partial content
            was continuable may only be redeemed the second way — if a same-body retry
            is rejected with a 400 saying the token must be redeemed by continuing the
            partial response, retry the second way instead. Either way: same workspace,
            same platform; a mismatch is a 400. Resending a token for an already-warm
            prefix is permitted but yields no additional credit.

            `null` when the refused model isn't eligible for a fallback credit.

          - `fallback_has_prefill_claim: bool`

            Whether the accompanying `fallback_credit_token` may be redeemed with the
            appended-assistant retry form. Only set when `fallback_credit_token` is
            present.

            `true`: retry by resending the same request body plus one appended
            `assistant` message whose content is this response's `content` with any
            trailing whitespace stripped from the final text block and unpaired
            `tool_use` blocks omitted (the same appended-turn shape described on
            `fallback_credit_token`), with the token attached. `false`: retry by
            resending the original request body unchanged, with the token attached —
            the appended-assistant form is not available for this refusal (no
            continuable partial content, or the request uses `output_format` or a
            `tool_choice` that forces tool use). One exception: when the request used
            `output_format` or a forced `tool_choice` and the refusal arrived after
            server tools (including MCP connector tools) had already executed, the
            token may not be redeemable by either retry form; if the exact-body retry
            is then rejected with a 400 saying the token must be redeemed by
            continuing the partial response, discard the token and retry without it.

            Advisory: if an appended-assistant retry is rejected with a 400 despite
            `true`, fall back to resending the original request body with the token.

          - `recommended_model: String`

            The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

          - `type: :refusal`

            - `:refusal`

        - `stop_reason: BetaStopReason`

          The reason that we stopped.

          This may be one the following values:

          * `"end_turn"`: the model reached a natural stopping point
          * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
          * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
          * `"tool_use"`: the model invoked one or more tools
          * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
          * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

          In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

          - `:end_turn`

          - `:max_tokens`

          - `:stop_sequence`

          - `:tool_use`

          - `:pause_turn`

          - `:compaction`

          - `:refusal`

          - `:model_context_window_exceeded`

        - `stop_sequence: String`

          Which custom stop sequence was generated, if any.

          This value will be a non-null string if one of your custom stop sequences was generated.

        - `type: :message`

          Object type.

          For Messages, this is always `"message"`.

          - `:message`

        - `usage: BetaUsage`

          Billing and rate-limit usage.

          Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

          Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

          For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

          Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

            - `ephemeral_1h_input_tokens: Integer`

              The number of input tokens used to create the 1 hour cache entry.

            - `ephemeral_5m_input_tokens: Integer`

              The number of input tokens used to create the 5 minute cache entry.

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `inference_geo: String`

            The geographic region where inference was performed for this request.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `iterations: BetaIterationsUsage`

            Per-iteration token usage breakdown.

            Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

            - Determine which iterations exceeded long context thresholds (>=200k tokens)
            - Calculate the true context window size from the last iteration
            - Understand token accumulation across server-side tool use loops

            - `class BetaMessageIterationUsage`

              Token usage for a sampling iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :message`

                Usage for a sampling iteration

                - `:message`

            - `class BetaCompactionIterationUsage`

              Token usage for a compaction iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :compaction`

                Usage for a compaction iteration

                - `:compaction`

            - `class BetaAdvisorMessageIterationUsage`

              Token usage for an advisor sub-inference iteration.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :advisor_message`

                Usage for an advisor sub-inference iteration

                - `:advisor_message`

            - `class BetaFallbackMessageIterationUsage`

              Token usage for the fallback-model attempt of a server-side fallback request.

              Produced in place of a `message` entry for whichever hop served the
              response. A declined hop produces the existing `message` entry. Whether
              a fallback model served the response is signalled by the presence of this
              entry in `usage.iterations`.

              - `cache_creation: BetaCacheCreation`

                Breakdown of cached tokens by TTL

              - `cache_creation_input_tokens: Integer`

                The number of input tokens used to create the cache entry.

              - `cache_read_input_tokens: Integer`

                The number of input tokens read from the cache.

              - `input_tokens: Integer`

                The number of input tokens which were used.

              - `model: Model`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `output_tokens: Integer`

                The number of output tokens which were used.

              - `type: :fallback_message`

                Usage for the fallback-model attempt that served the response

                - `:fallback_message`

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `output_tokens_details: BetaOutputTokensDetails`

            Breakdown of output tokens by category.

            `output_tokens` remains the inclusive, authoritative total used for billing.
            This object provides a read-only decomposition for observability — for example,
            how many of the billed output tokens were spent on internal reasoning that may
            have been summarized before being returned to you.

            - `thinking_tokens: Integer`

              Number of output tokens the model generated as internal reasoning, including
              the thinking-block delimiter tokens.

              Reflects the raw reasoning the model produced, not the (possibly shorter)
              summarized thinking text returned in the response body. Computed by
              re-tokenizing the raw reasoning text, so it may differ from the model's exact
              generation count by a small number of tokens. Always ≤ `output_tokens`;
              `output_tokens - thinking_tokens` approximates the non-reasoning output.

          - `server_tool_use: BetaServerToolUsage`

            The number of server tool requests.

            - `web_fetch_requests: Integer`

              The number of web fetch tool requests.

            - `web_search_requests: Integer`

              The number of web search tool requests.

          - `service_tier: :standard | :priority | :batch`

            If the request used the priority, standard, or batch tier.

            - `:standard`

            - `:priority`

            - `:batch`

          - `speed: :standard | :fast`

            The inference speed mode used for this request.

            - `:standard`

            - `:fast`

      - `type: :succeeded`

        - `:succeeded`

    - `class BetaMessageBatchErroredResult`

      - `error: BetaErrorResponse`

        - `error: BetaError`

          - `class BetaInvalidRequestError`

            - `message: String`

            - `type: :invalid_request_error`

              - `:invalid_request_error`

          - `class BetaAuthenticationError`

            - `message: String`

            - `type: :authentication_error`

              - `:authentication_error`

          - `class BetaBillingError`

            - `message: String`

            - `type: :billing_error`

              - `:billing_error`

          - `class BetaPermissionError`

            - `message: String`

            - `type: :permission_error`

              - `:permission_error`

          - `class BetaNotFoundError`

            - `message: String`

            - `type: :not_found_error`

              - `:not_found_error`

          - `class BetaRateLimitError`

            - `message: String`

            - `type: :rate_limit_error`

              - `:rate_limit_error`

          - `class BetaGatewayTimeoutError`

            - `message: String`

            - `type: :timeout_error`

              - `:timeout_error`

          - `class BetaAPIError`

            - `message: String`

            - `type: :api_error`

              - `:api_error`

          - `class BetaOverloadedError`

            - `message: String`

            - `type: :overloaded_error`

              - `:overloaded_error`

        - `request_id: String`

        - `type: :error`

          - `:error`

      - `type: :errored`

        - `:errored`

    - `class BetaMessageBatchCanceledResult`

      - `type: :canceled`

        - `:canceled`

    - `class BetaMessageBatchExpiredResult`

      - `type: :expired`

        - `:expired`

### Beta Message Batch Request Counts

- `class BetaMessageBatchRequestCounts`

  - `canceled: Integer`

    Number of requests in the Message Batch that have been canceled.

    This is zero until processing of the entire Message Batch has ended.

  - `errored: Integer`

    Number of requests in the Message Batch that encountered an error.

    This is zero until processing of the entire Message Batch has ended.

  - `expired: Integer`

    Number of requests in the Message Batch that have expired.

    This is zero until processing of the entire Message Batch has ended.

  - `processing: Integer`

    Number of requests in the Message Batch that are processing.

  - `succeeded: Integer`

    Number of requests in the Message Batch that have completed successfully.

    This is zero until processing of the entire Message Batch has ended.

### Beta Message Batch Result

- `BetaMessageBatchResult = BetaMessageBatchSucceededResult | BetaMessageBatchErroredResult | BetaMessageBatchCanceledResult | BetaMessageBatchExpiredResult`

  Processing result for this request.

  Contains a Message output if processing was successful, an error response if processing failed, or the reason why processing was not attempted, such as cancellation or expiration.

  - `class BetaMessageBatchSucceededResult`

    - `message: BetaMessage`

      - `id: String`

        Unique object identifier.

        The format and length of IDs may change over time.

      - `container: BetaContainer`

        Information about the container used in the request (for the code execution tool)

        - `id: String`

          Identifier for the container used in this request

        - `expires_at: Time`

          The time at which the container will expire.

        - `skills: Array[BetaSkill]`

          Skills loaded in the container

          - `skill_id: String`

            Skill ID

          - `type: :anthropic | :custom`

            Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

            - `:anthropic`

            - `:custom`

          - `version: String`

            Skill version or 'latest' for most recent version

      - `content: Array[BetaContentBlock]`

        Content generated by the model.

        This is an array of content blocks, each of which has a `type` that determines its shape.

        Example:

        ```json
        [{"type": "text", "text": "Hi, I'm Claude."}]
        ```

        If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

        For example, if the input `messages` were:

        ```json
        [
          {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
          {"role": "assistant", "content": "The best answer is ("}
        ]
        ```

        Then the response `content` might be:

        ```json
        [{"type": "text", "text": "B)"}]
        ```

        - `class BetaTextBlock`

          - `citations: Array[BetaTextCitation]`

            Citations supporting the text block.

            The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

            - `class BetaCitationCharLocation`

              - `cited_text: String`

              - `document_index: Integer`

              - `document_title: String`

              - `end_char_index: Integer`

              - `file_id: String`

              - `start_char_index: Integer`

              - `type: :char_location`

                - `:char_location`

            - `class BetaCitationPageLocation`

              - `cited_text: String`

              - `document_index: Integer`

              - `document_title: String`

              - `end_page_number: Integer`

              - `file_id: String`

              - `start_page_number: Integer`

              - `type: :page_location`

                - `:page_location`

            - `class BetaCitationContentBlockLocation`

              - `cited_text: String`

                The full text of the cited block range, concatenated.

                Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              - `document_index: Integer`

              - `document_title: String`

              - `end_block_index: Integer`

                Exclusive 0-based end index of the cited block range in the source's `content` array.

                Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

              - `file_id: String`

              - `start_block_index: Integer`

                0-based index of the first cited block in the source's `content` array.

              - `type: :content_block_location`

                - `:content_block_location`

            - `class BetaCitationsWebSearchResultLocation`

              - `cited_text: String`

              - `encrypted_index: String`

              - `title: String`

              - `type: :web_search_result_location`

                - `:web_search_result_location`

              - `url: String`

            - `class BetaCitationSearchResultLocation`

              - `cited_text: String`

                The full text of the cited block range, concatenated.

                Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

              - `end_block_index: Integer`

                Exclusive 0-based end index of the cited block range in the source's `content` array.

                Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

              - `search_result_index: Integer`

                0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

                Counted separately from `document_index`; server-side web search results are not included in this count.

              - `source: String`

              - `start_block_index: Integer`

                0-based index of the first cited block in the source's `content` array.

              - `title: String`

              - `type: :search_result_location`

                - `:search_result_location`

          - `text: String`

          - `type: :text`

            - `:text`

        - `class BetaThinkingBlock`

          - `signature: String`

          - `thinking: String`

          - `type: :thinking`

            - `:thinking`

        - `class BetaRedactedThinkingBlock`

          - `data: String`

          - `type: :redacted_thinking`

            - `:redacted_thinking`

        - `class BetaToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: String`

          - `type: :tool_use`

            - `:tool_use`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

              - `type: :direct`

                - `:direct`

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

              - `tool_id: String`

              - `type: :code_execution_20250825`

                - `:code_execution_20250825`

            - `class BetaServerToolCaller20260120`

              - `tool_id: String`

              - `type: :code_execution_20260120`

                - `:code_execution_20260120`

        - `class BetaServerToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: :advisor | :web_search | :web_fetch | 5 more`

            - `:advisor`

            - `:web_search`

            - `:web_fetch`

            - `:code_execution`

            - `:bash_code_execution`

            - `:text_editor_code_execution`

            - `:tool_search_tool_regex`

            - `:tool_search_tool_bm25`

          - `type: :server_tool_use`

            - `:server_tool_use`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaWebSearchToolResultBlock`

          - `content: BetaWebSearchToolResultBlockContent`

            - `class BetaWebSearchToolResultError`

              - `error_code: BetaWebSearchToolResultErrorCode`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:max_uses_exceeded`

                - `:too_many_requests`

                - `:query_too_long`

                - `:request_too_large`

              - `type: :web_search_tool_result_error`

                - `:web_search_tool_result_error`

            - `UnionMember1 = Array[BetaWebSearchResultBlock]`

              - `encrypted_content: String`

              - `page_age: String`

              - `title: String`

              - `type: :web_search_result`

                - `:web_search_result`

              - `url: String`

          - `tool_use_id: String`

          - `type: :web_search_tool_result`

            - `:web_search_tool_result`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaWebFetchToolResultBlock`

          - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

            - `class BetaWebFetchToolResultErrorBlock`

              - `error_code: BetaWebFetchToolResultErrorCode`

                - `:invalid_tool_input`

                - `:url_too_long`

                - `:url_not_allowed`

                - `:url_not_in_prior_context`

                - `:url_not_accessible`

                - `:unsupported_content_type`

                - `:too_many_requests`

                - `:max_uses_exceeded`

                - `:unavailable`

              - `type: :web_fetch_tool_result_error`

                - `:web_fetch_tool_result_error`

            - `class BetaWebFetchBlock`

              - `content: BetaDocumentBlock`

                - `citations: BetaCitationConfig`

                  Citation configuration for the document

                  - `enabled: bool`

                - `source: BetaBase64PDFSource | BetaPlainTextSource`

                  - `class BetaBase64PDFSource`

                    - `data: String`

                    - `media_type: :"application/pdf"`

                      - `:"application/pdf"`

                    - `type: :base64`

                      - `:base64`

                  - `class BetaPlainTextSource`

                    - `data: String`

                    - `media_type: :"text/plain"`

                      - `:"text/plain"`

                    - `type: :text`

                      - `:text`

                - `title: String`

                  The title of the document

                - `type: :document`

                  - `:document`

              - `retrieved_at: String`

                ISO 8601 timestamp when the content was retrieved

              - `type: :web_fetch_result`

                - `:web_fetch_result`

              - `url: String`

                Fetched content URL

          - `tool_use_id: String`

          - `type: :web_fetch_tool_result`

            - `:web_fetch_tool_result`

          - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

            Tool invocation directly from the model.

            - `class BetaDirectCaller`

              Tool invocation directly from the model.

            - `class BetaServerToolCaller`

              Tool invocation generated by a server-side tool.

            - `class BetaServerToolCaller20260120`

        - `class BetaAdvisorToolResultBlock`

          - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

            - `class BetaAdvisorToolResultError`

              - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

                - `:max_uses_exceeded`

                - `:prompt_too_long`

                - `:too_many_requests`

                - `:overloaded`

                - `:unavailable`

                - `:execution_time_exceeded`

                - `:model_not_found`

              - `type: :advisor_tool_result_error`

                - `:advisor_tool_result_error`

            - `class BetaAdvisorResultBlock`

              - `stop_reason: String`

                The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

              - `text: String`

              - `type: :advisor_result`

                - `:advisor_result`

            - `class BetaAdvisorRedactedResultBlock`

              - `encrypted_content: String`

                Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

              - `stop_reason: String`

                The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

              - `type: :advisor_redacted_result`

                - `:advisor_redacted_result`

          - `tool_use_id: String`

          - `type: :advisor_tool_result`

            - `:advisor_tool_result`

        - `class BetaCodeExecutionToolResultBlock`

          - `content: BetaCodeExecutionToolResultBlockContent`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `class BetaCodeExecutionToolResultError`

              - `error_code: BetaCodeExecutionToolResultErrorCode`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

              - `type: :code_execution_tool_result_error`

                - `:code_execution_tool_result_error`

            - `class BetaCodeExecutionResultBlock`

              - `content: Array[BetaCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :code_execution_output`

                  - `:code_execution_output`

              - `return_code: Integer`

              - `stderr: String`

              - `stdout: String`

              - `type: :code_execution_result`

                - `:code_execution_result`

            - `class BetaEncryptedCodeExecutionResultBlock`

              Code execution result with encrypted stdout for PFC + web_search results.

              - `content: Array[BetaCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :code_execution_output`

              - `encrypted_stdout: String`

              - `return_code: Integer`

              - `stderr: String`

              - `type: :encrypted_code_execution_result`

                - `:encrypted_code_execution_result`

          - `tool_use_id: String`

          - `type: :code_execution_tool_result`

            - `:code_execution_tool_result`

        - `class BetaBashCodeExecutionToolResultBlock`

          - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

            - `class BetaBashCodeExecutionToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

                - `:output_file_too_large`

              - `type: :bash_code_execution_tool_result_error`

                - `:bash_code_execution_tool_result_error`

            - `class BetaBashCodeExecutionResultBlock`

              - `content: Array[BetaBashCodeExecutionOutputBlock]`

                - `file_id: String`

                - `type: :bash_code_execution_output`

                  - `:bash_code_execution_output`

              - `return_code: Integer`

              - `stderr: String`

              - `stdout: String`

              - `type: :bash_code_execution_result`

                - `:bash_code_execution_result`

          - `tool_use_id: String`

          - `type: :bash_code_execution_tool_result`

            - `:bash_code_execution_tool_result`

        - `class BetaTextEditorCodeExecutionToolResultBlock`

          - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

            - `class BetaTextEditorCodeExecutionToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

                - `:file_not_found`

              - `error_message: String`

              - `type: :text_editor_code_execution_tool_result_error`

                - `:text_editor_code_execution_tool_result_error`

            - `class BetaTextEditorCodeExecutionViewResultBlock`

              - `content: String`

              - `file_type: :text | :image | :pdf`

                - `:text`

                - `:image`

                - `:pdf`

              - `num_lines: Integer`

              - `start_line: Integer`

              - `total_lines: Integer`

              - `type: :text_editor_code_execution_view_result`

                - `:text_editor_code_execution_view_result`

            - `class BetaTextEditorCodeExecutionCreateResultBlock`

              - `is_file_update: bool`

              - `type: :text_editor_code_execution_create_result`

                - `:text_editor_code_execution_create_result`

            - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

              - `lines: Array[String]`

              - `new_lines: Integer`

              - `new_start: Integer`

              - `old_lines: Integer`

              - `old_start: Integer`

              - `type: :text_editor_code_execution_str_replace_result`

                - `:text_editor_code_execution_str_replace_result`

          - `tool_use_id: String`

          - `type: :text_editor_code_execution_tool_result`

            - `:text_editor_code_execution_tool_result`

        - `class BetaToolSearchToolResultBlock`

          - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

            - `class BetaToolSearchToolResultError`

              - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

                - `:invalid_tool_input`

                - `:unavailable`

                - `:too_many_requests`

                - `:execution_time_exceeded`

              - `error_message: String`

              - `type: :tool_search_tool_result_error`

                - `:tool_search_tool_result_error`

            - `class BetaToolSearchToolSearchResultBlock`

              - `tool_references: Array[BetaToolReferenceBlock]`

                - `tool_name: String`

                - `type: :tool_reference`

                  - `:tool_reference`

              - `type: :tool_search_tool_search_result`

                - `:tool_search_tool_search_result`

          - `tool_use_id: String`

          - `type: :tool_search_tool_result`

            - `:tool_search_tool_result`

        - `class BetaMCPToolUseBlock`

          - `id: String`

          - `input: Hash[Symbol, untyped]`

          - `name: String`

            The name of the MCP tool

          - `server_name: String`

            The name of the MCP server

          - `type: :mcp_tool_use`

            - `:mcp_tool_use`

        - `class BetaMCPToolResultBlock`

          - `content: String | Array[BetaTextBlock]`

            - `String = String`

            - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

              - `citations: Array[BetaTextCitation]`

                Citations supporting the text block.

                The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

              - `text: String`

              - `type: :text`

          - `is_error: bool`

          - `tool_use_id: String`

          - `type: :mcp_tool_result`

            - `:mcp_tool_result`

        - `class BetaContainerUploadBlock`

          Response model for a file uploaded to the container.

          - `file_id: String`

          - `type: :container_upload`

            - `:container_upload`

        - `class BetaCompactionBlock`

          A compaction block returned when autocompact is triggered.

          When content is None, it indicates the compaction failed to produce a valid
          summary (e.g., malformed output from the model). Clients may round-trip
          compaction blocks with null content; the server treats them as no-ops.

          - `content: String`

            Summary of compacted content, or null if compaction failed

          - `encrypted_content: String`

            Opaque metadata from prior compaction, to be round-tripped verbatim

          - `type: :compaction`

            - `:compaction`

        - `class BetaFallbackBlock`

          Marks the point in `content` where one model's output gives way to the next.

          One block appears per hop where a preceding model actually ran this turn and
          declined. A turn routed directly by the sticky decision has no such boundary
          and carries no block — the signal for whether a fallback model served the
          response is the presence of a `fallback_message` entry in
          `usage.iterations`, not this block.

          The block is treated like a server-tool content block for streaming: it
          arrives via the standard `content_block_start` / `content_block_stop`
          pair and carries no deltas.

          - `from: BetaFallbackInfo`

            The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

                The model that will complete your prompt.

                See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

                - `:"claude-fable-5"`

                  Next generation of intelligence for the hardest knowledge work and coding problems

                - `:"claude-mythos-5"`

                  Most capable model for cybersecurity and biology research

                - `:"claude-opus-4-8"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-opus-4-7"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-mythos-preview"`

                  New class of intelligence, strongest in coding and cybersecurity

                - `:"claude-opus-4-6"`

                  Frontier intelligence for long-running agents and coding

                - `:"claude-sonnet-4-6"`

                  Best combination of speed and intelligence

                - `:"claude-haiku-4-5"`

                  Fastest model with near-frontier intelligence

                - `:"claude-haiku-4-5-20251001"`

                  Fastest model with near-frontier intelligence

                - `:"claude-opus-4-5"`

                  Premium model combining maximum intelligence with practical performance

                - `:"claude-opus-4-5-20251101"`

                  Premium model combining maximum intelligence with practical performance

                - `:"claude-sonnet-4-5"`

                  High-performance model for agents and coding

                - `:"claude-sonnet-4-5-20250929"`

                  High-performance model for agents and coding

                - `:"claude-opus-4-1"`

                  Exceptional model for specialized complex tasks

                - `:"claude-opus-4-1-20250805"`

                  Exceptional model for specialized complex tasks

                - `:"claude-opus-4-0"`

                  Powerful model for complex tasks

                - `:"claude-opus-4-20250514"`

                  Powerful model for complex tasks

                - `:"claude-sonnet-4-0"`

                  High-performance model with extended thinking

                - `:"claude-sonnet-4-20250514"`

                  High-performance model with extended thinking

                - `:"claude-3-haiku-20240307"`

                  Fast and cost-effective model

              - `String = String`

          - `to: BetaFallbackInfo`

            The fallback model producing the content that follows this block. Its `model` is always the canonical id.

          - `type: :fallback`

            - `:fallback`

      - `context_management: BetaContextManagementResponse`

        Context management response.

        Information about context management strategies applied during the request.

        - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

          List of context management edits that were applied.

          - `class BetaClearToolUses20250919EditResponse`

            - `cleared_input_tokens: Integer`

              Number of input tokens cleared by this edit.

            - `cleared_tool_uses: Integer`

              Number of tool uses that were cleared.

            - `type: :clear_tool_uses_20250919`

              The type of context management edit applied.

              - `:clear_tool_uses_20250919`

          - `class BetaClearThinking20251015EditResponse`

            - `cleared_input_tokens: Integer`

              Number of input tokens cleared by this edit.

            - `cleared_thinking_turns: Integer`

              Number of thinking turns that were cleared.

            - `type: :clear_thinking_20251015`

              The type of context management edit applied.

              - `:clear_thinking_20251015`

      - `diagnostics: BetaDiagnostics`

        Response envelope for request-level diagnostics. Present (possibly
        null) whenever the caller supplied `diagnostics` on the request.

        - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

          Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

          - `class BetaCacheMissModelChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :model_changed`

              - `:model_changed`

          - `class BetaCacheMissSystemChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :system_changed`

              - `:system_changed`

          - `class BetaCacheMissToolsChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :tools_changed`

              - `:tools_changed`

          - `class BetaCacheMissMessagesChanged`

            - `cache_missed_input_tokens: Integer`

              Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

            - `type: :messages_changed`

              - `:messages_changed`

          - `class BetaCacheMissPreviousMessageNotFound`

            - `type: :previous_message_not_found`

              - `:previous_message_not_found`

          - `class BetaCacheMissUnavailable`

            - `type: :unavailable`

              - `:unavailable`

      - `model: Model`

        The model that will complete your prompt.

        See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

      - `role: :assistant`

        Conversational role of the generated message.

        This will always be `"assistant"`.

        - `:assistant`

      - `stop_details: BetaRefusalStopDetails`

        Structured information about a refusal.

        - `category: :cyber | :bio | :reasoning_extraction`

          The policy category that triggered the refusal.

          `null` when the refusal doesn't map to a named category.

          - `:cyber`

          - `:bio`

          - `:reasoning_extraction`

        - `explanation: String`

          Human-readable explanation of the refusal.

          This text is not guaranteed to be stable. `null` when no explanation is available for the category.

        - `fallback_credit_token: String`

          Opaque code that refunds the cache-miss cost when retrying this refused
          request on the fallback model. Pass it as `fallback_credit_token` on the
          retry request. Expires 5 minutes after the refusal.

          The retry is sent either with the same request body (`system`, `messages`,
          `tools`, and other render-shaping fields), or with the same body plus one
          appended `assistant` message whose content is the partial text (with any
          trailing whitespace stripped from the final text block) and paired
          server-tool blocks from this refusal — which also authorizes that
          appended turn as an assistant-prefill continuation on models that otherwise
          disallow prefill. A token minted mid-server-tool-loop whose partial content
          was continuable may only be redeemed the second way — if a same-body retry
          is rejected with a 400 saying the token must be redeemed by continuing the
          partial response, retry the second way instead. Either way: same workspace,
          same platform; a mismatch is a 400. Resending a token for an already-warm
          prefix is permitted but yields no additional credit.

          `null` when the refused model isn't eligible for a fallback credit.

        - `fallback_has_prefill_claim: bool`

          Whether the accompanying `fallback_credit_token` may be redeemed with the
          appended-assistant retry form. Only set when `fallback_credit_token` is
          present.

          `true`: retry by resending the same request body plus one appended
          `assistant` message whose content is this response's `content` with any
          trailing whitespace stripped from the final text block and unpaired
          `tool_use` blocks omitted (the same appended-turn shape described on
          `fallback_credit_token`), with the token attached. `false`: retry by
          resending the original request body unchanged, with the token attached —
          the appended-assistant form is not available for this refusal (no
          continuable partial content, or the request uses `output_format` or a
          `tool_choice` that forces tool use). One exception: when the request used
          `output_format` or a forced `tool_choice` and the refusal arrived after
          server tools (including MCP connector tools) had already executed, the
          token may not be redeemable by either retry form; if the exact-body retry
          is then rejected with a 400 saying the token must be redeemed by
          continuing the partial response, discard the token and retry without it.

          Advisory: if an appended-assistant retry is rejected with a 400 despite
          `true`, fall back to resending the original request body with the token.

        - `recommended_model: String`

          The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

        - `type: :refusal`

          - `:refusal`

      - `stop_reason: BetaStopReason`

        The reason that we stopped.

        This may be one the following values:

        * `"end_turn"`: the model reached a natural stopping point
        * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
        * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
        * `"tool_use"`: the model invoked one or more tools
        * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
        * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

        In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

        - `:end_turn`

        - `:max_tokens`

        - `:stop_sequence`

        - `:tool_use`

        - `:pause_turn`

        - `:compaction`

        - `:refusal`

        - `:model_context_window_exceeded`

      - `stop_sequence: String`

        Which custom stop sequence was generated, if any.

        This value will be a non-null string if one of your custom stop sequences was generated.

      - `type: :message`

        Object type.

        For Messages, this is always `"message"`.

        - `:message`

      - `usage: BetaUsage`

        Billing and rate-limit usage.

        Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

        Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

        For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

        Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

        - `cache_creation: BetaCacheCreation`

          Breakdown of cached tokens by TTL

          - `ephemeral_1h_input_tokens: Integer`

            The number of input tokens used to create the 1 hour cache entry.

          - `ephemeral_5m_input_tokens: Integer`

            The number of input tokens used to create the 5 minute cache entry.

        - `cache_creation_input_tokens: Integer`

          The number of input tokens used to create the cache entry.

        - `cache_read_input_tokens: Integer`

          The number of input tokens read from the cache.

        - `inference_geo: String`

          The geographic region where inference was performed for this request.

        - `input_tokens: Integer`

          The number of input tokens which were used.

        - `iterations: BetaIterationsUsage`

          Per-iteration token usage breakdown.

          Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

          - Determine which iterations exceeded long context thresholds (>=200k tokens)
          - Calculate the true context window size from the last iteration
          - Understand token accumulation across server-side tool use loops

          - `class BetaMessageIterationUsage`

            Token usage for a sampling iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :message`

              Usage for a sampling iteration

              - `:message`

          - `class BetaCompactionIterationUsage`

            Token usage for a compaction iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :compaction`

              Usage for a compaction iteration

              - `:compaction`

          - `class BetaAdvisorMessageIterationUsage`

            Token usage for an advisor sub-inference iteration.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :advisor_message`

              Usage for an advisor sub-inference iteration

              - `:advisor_message`

          - `class BetaFallbackMessageIterationUsage`

            Token usage for the fallback-model attempt of a server-side fallback request.

            Produced in place of a `message` entry for whichever hop served the
            response. A declined hop produces the existing `message` entry. Whether
            a fallback model served the response is signalled by the presence of this
            entry in `usage.iterations`.

            - `cache_creation: BetaCacheCreation`

              Breakdown of cached tokens by TTL

            - `cache_creation_input_tokens: Integer`

              The number of input tokens used to create the cache entry.

            - `cache_read_input_tokens: Integer`

              The number of input tokens read from the cache.

            - `input_tokens: Integer`

              The number of input tokens which were used.

            - `model: Model`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `output_tokens: Integer`

              The number of output tokens which were used.

            - `type: :fallback_message`

              Usage for the fallback-model attempt that served the response

              - `:fallback_message`

        - `output_tokens: Integer`

          The number of output tokens which were used.

        - `output_tokens_details: BetaOutputTokensDetails`

          Breakdown of output tokens by category.

          `output_tokens` remains the inclusive, authoritative total used for billing.
          This object provides a read-only decomposition for observability — for example,
          how many of the billed output tokens were spent on internal reasoning that may
          have been summarized before being returned to you.

          - `thinking_tokens: Integer`

            Number of output tokens the model generated as internal reasoning, including
            the thinking-block delimiter tokens.

            Reflects the raw reasoning the model produced, not the (possibly shorter)
            summarized thinking text returned in the response body. Computed by
            re-tokenizing the raw reasoning text, so it may differ from the model's exact
            generation count by a small number of tokens. Always ≤ `output_tokens`;
            `output_tokens - thinking_tokens` approximates the non-reasoning output.

        - `server_tool_use: BetaServerToolUsage`

          The number of server tool requests.

          - `web_fetch_requests: Integer`

            The number of web fetch tool requests.

          - `web_search_requests: Integer`

            The number of web search tool requests.

        - `service_tier: :standard | :priority | :batch`

          If the request used the priority, standard, or batch tier.

          - `:standard`

          - `:priority`

          - `:batch`

        - `speed: :standard | :fast`

          The inference speed mode used for this request.

          - `:standard`

          - `:fast`

    - `type: :succeeded`

      - `:succeeded`

  - `class BetaMessageBatchErroredResult`

    - `error: BetaErrorResponse`

      - `error: BetaError`

        - `class BetaInvalidRequestError`

          - `message: String`

          - `type: :invalid_request_error`

            - `:invalid_request_error`

        - `class BetaAuthenticationError`

          - `message: String`

          - `type: :authentication_error`

            - `:authentication_error`

        - `class BetaBillingError`

          - `message: String`

          - `type: :billing_error`

            - `:billing_error`

        - `class BetaPermissionError`

          - `message: String`

          - `type: :permission_error`

            - `:permission_error`

        - `class BetaNotFoundError`

          - `message: String`

          - `type: :not_found_error`

            - `:not_found_error`

        - `class BetaRateLimitError`

          - `message: String`

          - `type: :rate_limit_error`

            - `:rate_limit_error`

        - `class BetaGatewayTimeoutError`

          - `message: String`

          - `type: :timeout_error`

            - `:timeout_error`

        - `class BetaAPIError`

          - `message: String`

          - `type: :api_error`

            - `:api_error`

        - `class BetaOverloadedError`

          - `message: String`

          - `type: :overloaded_error`

            - `:overloaded_error`

      - `request_id: String`

      - `type: :error`

        - `:error`

    - `type: :errored`

      - `:errored`

  - `class BetaMessageBatchCanceledResult`

    - `type: :canceled`

      - `:canceled`

  - `class BetaMessageBatchExpiredResult`

    - `type: :expired`

      - `:expired`

### Beta Message Batch Succeeded Result

- `class BetaMessageBatchSucceededResult`

  - `message: BetaMessage`

    - `id: String`

      Unique object identifier.

      The format and length of IDs may change over time.

    - `container: BetaContainer`

      Information about the container used in the request (for the code execution tool)

      - `id: String`

        Identifier for the container used in this request

      - `expires_at: Time`

        The time at which the container will expire.

      - `skills: Array[BetaSkill]`

        Skills loaded in the container

        - `skill_id: String`

          Skill ID

        - `type: :anthropic | :custom`

          Type of skill - either 'anthropic' (built-in) or 'custom' (user-defined)

          - `:anthropic`

          - `:custom`

        - `version: String`

          Skill version or 'latest' for most recent version

    - `content: Array[BetaContentBlock]`

      Content generated by the model.

      This is an array of content blocks, each of which has a `type` that determines its shape.

      Example:

      ```json
      [{"type": "text", "text": "Hi, I'm Claude."}]
      ```

      If the request input `messages` ended with an `assistant` turn, then the response `content` will continue directly from that last turn. You can use this to constrain the model's output.

      For example, if the input `messages` were:

      ```json
      [
        {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
        {"role": "assistant", "content": "The best answer is ("}
      ]
      ```

      Then the response `content` might be:

      ```json
      [{"type": "text", "text": "B)"}]
      ```

      - `class BetaTextBlock`

        - `citations: Array[BetaTextCitation]`

          Citations supporting the text block.

          The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

          - `class BetaCitationCharLocation`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_char_index: Integer`

            - `file_id: String`

            - `start_char_index: Integer`

            - `type: :char_location`

              - `:char_location`

          - `class BetaCitationPageLocation`

            - `cited_text: String`

            - `document_index: Integer`

            - `document_title: String`

            - `end_page_number: Integer`

            - `file_id: String`

            - `start_page_number: Integer`

            - `type: :page_location`

              - `:page_location`

          - `class BetaCitationContentBlockLocation`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `document_index: Integer`

            - `document_title: String`

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `file_id: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `type: :content_block_location`

              - `:content_block_location`

          - `class BetaCitationsWebSearchResultLocation`

            - `cited_text: String`

            - `encrypted_index: String`

            - `title: String`

            - `type: :web_search_result_location`

              - `:web_search_result_location`

            - `url: String`

          - `class BetaCitationSearchResultLocation`

            - `cited_text: String`

              The full text of the cited block range, concatenated.

              Always equals the contents of `content[start_block_index:end_block_index]` joined together. The text block is the minimal citable unit; this field is never a substring of a single block. Not counted toward output tokens, and not counted toward input tokens when sent back in subsequent turns.

            - `end_block_index: Integer`

              Exclusive 0-based end index of the cited block range in the source's `content` array.

              Always greater than `start_block_index`; a single-block citation has `end_block_index = start_block_index + 1`.

            - `search_result_index: Integer`

              0-based index of the cited search result among all `search_result` content blocks in the request, in the order they appear across messages and tool results.

              Counted separately from `document_index`; server-side web search results are not included in this count.

            - `source: String`

            - `start_block_index: Integer`

              0-based index of the first cited block in the source's `content` array.

            - `title: String`

            - `type: :search_result_location`

              - `:search_result_location`

        - `text: String`

        - `type: :text`

          - `:text`

      - `class BetaThinkingBlock`

        - `signature: String`

        - `thinking: String`

        - `type: :thinking`

          - `:thinking`

      - `class BetaRedactedThinkingBlock`

        - `data: String`

        - `type: :redacted_thinking`

          - `:redacted_thinking`

      - `class BetaToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

        - `type: :tool_use`

          - `:tool_use`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

            - `type: :direct`

              - `:direct`

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

            - `tool_id: String`

            - `type: :code_execution_20250825`

              - `:code_execution_20250825`

          - `class BetaServerToolCaller20260120`

            - `tool_id: String`

            - `type: :code_execution_20260120`

              - `:code_execution_20260120`

      - `class BetaServerToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: :advisor | :web_search | :web_fetch | 5 more`

          - `:advisor`

          - `:web_search`

          - `:web_fetch`

          - `:code_execution`

          - `:bash_code_execution`

          - `:text_editor_code_execution`

          - `:tool_search_tool_regex`

          - `:tool_search_tool_bm25`

        - `type: :server_tool_use`

          - `:server_tool_use`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebSearchToolResultBlock`

        - `content: BetaWebSearchToolResultBlockContent`

          - `class BetaWebSearchToolResultError`

            - `error_code: BetaWebSearchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:max_uses_exceeded`

              - `:too_many_requests`

              - `:query_too_long`

              - `:request_too_large`

            - `type: :web_search_tool_result_error`

              - `:web_search_tool_result_error`

          - `UnionMember1 = Array[BetaWebSearchResultBlock]`

            - `encrypted_content: String`

            - `page_age: String`

            - `title: String`

            - `type: :web_search_result`

              - `:web_search_result`

            - `url: String`

        - `tool_use_id: String`

        - `type: :web_search_tool_result`

          - `:web_search_tool_result`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaWebFetchToolResultBlock`

        - `content: BetaWebFetchToolResultErrorBlock | BetaWebFetchBlock`

          - `class BetaWebFetchToolResultErrorBlock`

            - `error_code: BetaWebFetchToolResultErrorCode`

              - `:invalid_tool_input`

              - `:url_too_long`

              - `:url_not_allowed`

              - `:url_not_in_prior_context`

              - `:url_not_accessible`

              - `:unsupported_content_type`

              - `:too_many_requests`

              - `:max_uses_exceeded`

              - `:unavailable`

            - `type: :web_fetch_tool_result_error`

              - `:web_fetch_tool_result_error`

          - `class BetaWebFetchBlock`

            - `content: BetaDocumentBlock`

              - `citations: BetaCitationConfig`

                Citation configuration for the document

                - `enabled: bool`

              - `source: BetaBase64PDFSource | BetaPlainTextSource`

                - `class BetaBase64PDFSource`

                  - `data: String`

                  - `media_type: :"application/pdf"`

                    - `:"application/pdf"`

                  - `type: :base64`

                    - `:base64`

                - `class BetaPlainTextSource`

                  - `data: String`

                  - `media_type: :"text/plain"`

                    - `:"text/plain"`

                  - `type: :text`

                    - `:text`

              - `title: String`

                The title of the document

              - `type: :document`

                - `:document`

            - `retrieved_at: String`

              ISO 8601 timestamp when the content was retrieved

            - `type: :web_fetch_result`

              - `:web_fetch_result`

            - `url: String`

              Fetched content URL

        - `tool_use_id: String`

        - `type: :web_fetch_tool_result`

          - `:web_fetch_tool_result`

        - `caller_: BetaDirectCaller | BetaServerToolCaller | BetaServerToolCaller20260120`

          Tool invocation directly from the model.

          - `class BetaDirectCaller`

            Tool invocation directly from the model.

          - `class BetaServerToolCaller`

            Tool invocation generated by a server-side tool.

          - `class BetaServerToolCaller20260120`

      - `class BetaAdvisorToolResultBlock`

        - `content: BetaAdvisorToolResultError | BetaAdvisorResultBlock | BetaAdvisorRedactedResultBlock`

          - `class BetaAdvisorToolResultError`

            - `error_code: :max_uses_exceeded | :prompt_too_long | :too_many_requests | 4 more`

              - `:max_uses_exceeded`

              - `:prompt_too_long`

              - `:too_many_requests`

              - `:overloaded`

              - `:unavailable`

              - `:execution_time_exceeded`

              - `:model_not_found`

            - `type: :advisor_tool_result_error`

              - `:advisor_tool_result_error`

          - `class BetaAdvisorResultBlock`

            - `stop_reason: String`

              The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`). `max_tokens` indicates the advisor's output was truncated at the tool's `max_tokens` value or the advisor model's policy cap.

            - `text: String`

            - `type: :advisor_result`

              - `:advisor_result`

          - `class BetaAdvisorRedactedResultBlock`

            - `encrypted_content: String`

              Opaque blob containing the advisor's output. Round-trip verbatim; do not inspect or modify.

            - `stop_reason: String`

              The advisor sub-inference's stop reason (same values as the top-level message `stop_reason`).

            - `type: :advisor_redacted_result`

              - `:advisor_redacted_result`

        - `tool_use_id: String`

        - `type: :advisor_tool_result`

          - `:advisor_tool_result`

      - `class BetaCodeExecutionToolResultBlock`

        - `content: BetaCodeExecutionToolResultBlockContent`

          Code execution result with encrypted stdout for PFC + web_search results.

          - `class BetaCodeExecutionToolResultError`

            - `error_code: BetaCodeExecutionToolResultErrorCode`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `type: :code_execution_tool_result_error`

              - `:code_execution_tool_result_error`

          - `class BetaCodeExecutionResultBlock`

            - `content: Array[BetaCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :code_execution_output`

                - `:code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :code_execution_result`

              - `:code_execution_result`

          - `class BetaEncryptedCodeExecutionResultBlock`

            Code execution result with encrypted stdout for PFC + web_search results.

            - `content: Array[BetaCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :code_execution_output`

            - `encrypted_stdout: String`

            - `return_code: Integer`

            - `stderr: String`

            - `type: :encrypted_code_execution_result`

              - `:encrypted_code_execution_result`

        - `tool_use_id: String`

        - `type: :code_execution_tool_result`

          - `:code_execution_tool_result`

      - `class BetaBashCodeExecutionToolResultBlock`

        - `content: BetaBashCodeExecutionToolResultError | BetaBashCodeExecutionResultBlock`

          - `class BetaBashCodeExecutionToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:output_file_too_large`

            - `type: :bash_code_execution_tool_result_error`

              - `:bash_code_execution_tool_result_error`

          - `class BetaBashCodeExecutionResultBlock`

            - `content: Array[BetaBashCodeExecutionOutputBlock]`

              - `file_id: String`

              - `type: :bash_code_execution_output`

                - `:bash_code_execution_output`

            - `return_code: Integer`

            - `stderr: String`

            - `stdout: String`

            - `type: :bash_code_execution_result`

              - `:bash_code_execution_result`

        - `tool_use_id: String`

        - `type: :bash_code_execution_tool_result`

          - `:bash_code_execution_tool_result`

      - `class BetaTextEditorCodeExecutionToolResultBlock`

        - `content: BetaTextEditorCodeExecutionToolResultError | BetaTextEditorCodeExecutionViewResultBlock | BetaTextEditorCodeExecutionCreateResultBlock | BetaTextEditorCodeExecutionStrReplaceResultBlock`

          - `class BetaTextEditorCodeExecutionToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | 2 more`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

              - `:file_not_found`

            - `error_message: String`

            - `type: :text_editor_code_execution_tool_result_error`

              - `:text_editor_code_execution_tool_result_error`

          - `class BetaTextEditorCodeExecutionViewResultBlock`

            - `content: String`

            - `file_type: :text | :image | :pdf`

              - `:text`

              - `:image`

              - `:pdf`

            - `num_lines: Integer`

            - `start_line: Integer`

            - `total_lines: Integer`

            - `type: :text_editor_code_execution_view_result`

              - `:text_editor_code_execution_view_result`

          - `class BetaTextEditorCodeExecutionCreateResultBlock`

            - `is_file_update: bool`

            - `type: :text_editor_code_execution_create_result`

              - `:text_editor_code_execution_create_result`

          - `class BetaTextEditorCodeExecutionStrReplaceResultBlock`

            - `lines: Array[String]`

            - `new_lines: Integer`

            - `new_start: Integer`

            - `old_lines: Integer`

            - `old_start: Integer`

            - `type: :text_editor_code_execution_str_replace_result`

              - `:text_editor_code_execution_str_replace_result`

        - `tool_use_id: String`

        - `type: :text_editor_code_execution_tool_result`

          - `:text_editor_code_execution_tool_result`

      - `class BetaToolSearchToolResultBlock`

        - `content: BetaToolSearchToolResultError | BetaToolSearchToolSearchResultBlock`

          - `class BetaToolSearchToolResultError`

            - `error_code: :invalid_tool_input | :unavailable | :too_many_requests | :execution_time_exceeded`

              - `:invalid_tool_input`

              - `:unavailable`

              - `:too_many_requests`

              - `:execution_time_exceeded`

            - `error_message: String`

            - `type: :tool_search_tool_result_error`

              - `:tool_search_tool_result_error`

          - `class BetaToolSearchToolSearchResultBlock`

            - `tool_references: Array[BetaToolReferenceBlock]`

              - `tool_name: String`

              - `type: :tool_reference`

                - `:tool_reference`

            - `type: :tool_search_tool_search_result`

              - `:tool_search_tool_search_result`

        - `tool_use_id: String`

        - `type: :tool_search_tool_result`

          - `:tool_search_tool_result`

      - `class BetaMCPToolUseBlock`

        - `id: String`

        - `input: Hash[Symbol, untyped]`

        - `name: String`

          The name of the MCP tool

        - `server_name: String`

          The name of the MCP server

        - `type: :mcp_tool_use`

          - `:mcp_tool_use`

      - `class BetaMCPToolResultBlock`

        - `content: String | Array[BetaTextBlock]`

          - `String = String`

          - `BetaMCPToolResultBlockContent = Array[BetaTextBlock]`

            - `citations: Array[BetaTextCitation]`

              Citations supporting the text block.

              The type of citation returned will depend on the type of document being cited. Citing a PDF results in `page_location`, plain text results in `char_location`, and content document results in `content_block_location`.

            - `text: String`

            - `type: :text`

        - `is_error: bool`

        - `tool_use_id: String`

        - `type: :mcp_tool_result`

          - `:mcp_tool_result`

      - `class BetaContainerUploadBlock`

        Response model for a file uploaded to the container.

        - `file_id: String`

        - `type: :container_upload`

          - `:container_upload`

      - `class BetaCompactionBlock`

        A compaction block returned when autocompact is triggered.

        When content is None, it indicates the compaction failed to produce a valid
        summary (e.g., malformed output from the model). Clients may round-trip
        compaction blocks with null content; the server treats them as no-ops.

        - `content: String`

          Summary of compacted content, or null if compaction failed

        - `encrypted_content: String`

          Opaque metadata from prior compaction, to be round-tripped verbatim

        - `type: :compaction`

          - `:compaction`

      - `class BetaFallbackBlock`

        Marks the point in `content` where one model's output gives way to the next.

        One block appears per hop where a preceding model actually ran this turn and
        declined. A turn routed directly by the sticky decision has no such boundary
        and carries no block — the signal for whether a fallback model served the
        response is the presence of a `fallback_message` entry in
        `usage.iterations`, not this block.

        The block is treated like a server-tool content block for streaming: it
        arrives via the standard `content_block_start` / `content_block_stop`
        pair and carries no deltas.

        - `from: BetaFallbackInfo`

          The model whose output ends at this point — the model that declined at this hop. When the declining hop is the requested model, its `model` echoes the top-level `model` string the caller sent (alias or canonical); when the declining hop is a fallback model, its `model` is that model's canonical id.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

            - `Model = :"claude-fable-5" | :"claude-mythos-5" | :"claude-opus-4-8" | 17 more`

              The model that will complete your prompt.

              See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

              - `:"claude-fable-5"`

                Next generation of intelligence for the hardest knowledge work and coding problems

              - `:"claude-mythos-5"`

                Most capable model for cybersecurity and biology research

              - `:"claude-opus-4-8"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-opus-4-7"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-mythos-preview"`

                New class of intelligence, strongest in coding and cybersecurity

              - `:"claude-opus-4-6"`

                Frontier intelligence for long-running agents and coding

              - `:"claude-sonnet-4-6"`

                Best combination of speed and intelligence

              - `:"claude-haiku-4-5"`

                Fastest model with near-frontier intelligence

              - `:"claude-haiku-4-5-20251001"`

                Fastest model with near-frontier intelligence

              - `:"claude-opus-4-5"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-opus-4-5-20251101"`

                Premium model combining maximum intelligence with practical performance

              - `:"claude-sonnet-4-5"`

                High-performance model for agents and coding

              - `:"claude-sonnet-4-5-20250929"`

                High-performance model for agents and coding

              - `:"claude-opus-4-1"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-1-20250805"`

                Exceptional model for specialized complex tasks

              - `:"claude-opus-4-0"`

                Powerful model for complex tasks

              - `:"claude-opus-4-20250514"`

                Powerful model for complex tasks

              - `:"claude-sonnet-4-0"`

                High-performance model with extended thinking

              - `:"claude-sonnet-4-20250514"`

                High-performance model with extended thinking

              - `:"claude-3-haiku-20240307"`

                Fast and cost-effective model

            - `String = String`

        - `to: BetaFallbackInfo`

          The fallback model producing the content that follows this block. Its `model` is always the canonical id.

        - `type: :fallback`

          - `:fallback`

    - `context_management: BetaContextManagementResponse`

      Context management response.

      Information about context management strategies applied during the request.

      - `applied_edits: Array[BetaClearToolUses20250919EditResponse | BetaClearThinking20251015EditResponse]`

        List of context management edits that were applied.

        - `class BetaClearToolUses20250919EditResponse`

          - `cleared_input_tokens: Integer`

            Number of input tokens cleared by this edit.

          - `cleared_tool_uses: Integer`

            Number of tool uses that were cleared.

          - `type: :clear_tool_uses_20250919`

            The type of context management edit applied.

            - `:clear_tool_uses_20250919`

        - `class BetaClearThinking20251015EditResponse`

          - `cleared_input_tokens: Integer`

            Number of input tokens cleared by this edit.

          - `cleared_thinking_turns: Integer`

            Number of thinking turns that were cleared.

          - `type: :clear_thinking_20251015`

            The type of context management edit applied.

            - `:clear_thinking_20251015`

    - `diagnostics: BetaDiagnostics`

      Response envelope for request-level diagnostics. Present (possibly
      null) whenever the caller supplied `diagnostics` on the request.

      - `cache_miss_reason: BetaCacheMissModelChanged | BetaCacheMissSystemChanged | BetaCacheMissToolsChanged | 3 more`

        Explains why the prompt cache could not fully reuse the prefix from the request identified by `diagnostics.previous_message_id`. `null` means diagnosis is still pending — the response was serialized before the background comparison completed.

        - `class BetaCacheMissModelChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :model_changed`

            - `:model_changed`

        - `class BetaCacheMissSystemChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :system_changed`

            - `:system_changed`

        - `class BetaCacheMissToolsChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :tools_changed`

            - `:tools_changed`

        - `class BetaCacheMissMessagesChanged`

          - `cache_missed_input_tokens: Integer`

            Approximate number of input tokens that would have been read from cache had the prefix matched the previous request.

          - `type: :messages_changed`

            - `:messages_changed`

        - `class BetaCacheMissPreviousMessageNotFound`

          - `type: :previous_message_not_found`

            - `:previous_message_not_found`

        - `class BetaCacheMissUnavailable`

          - `type: :unavailable`

            - `:unavailable`

    - `model: Model`

      The model that will complete your prompt.

      See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

    - `role: :assistant`

      Conversational role of the generated message.

      This will always be `"assistant"`.

      - `:assistant`

    - `stop_details: BetaRefusalStopDetails`

      Structured information about a refusal.

      - `category: :cyber | :bio | :reasoning_extraction`

        The policy category that triggered the refusal.

        `null` when the refusal doesn't map to a named category.

        - `:cyber`

        - `:bio`

        - `:reasoning_extraction`

      - `explanation: String`

        Human-readable explanation of the refusal.

        This text is not guaranteed to be stable. `null` when no explanation is available for the category.

      - `fallback_credit_token: String`

        Opaque code that refunds the cache-miss cost when retrying this refused
        request on the fallback model. Pass it as `fallback_credit_token` on the
        retry request. Expires 5 minutes after the refusal.

        The retry is sent either with the same request body (`system`, `messages`,
        `tools`, and other render-shaping fields), or with the same body plus one
        appended `assistant` message whose content is the partial text (with any
        trailing whitespace stripped from the final text block) and paired
        server-tool blocks from this refusal — which also authorizes that
        appended turn as an assistant-prefill continuation on models that otherwise
        disallow prefill. A token minted mid-server-tool-loop whose partial content
        was continuable may only be redeemed the second way — if a same-body retry
        is rejected with a 400 saying the token must be redeemed by continuing the
        partial response, retry the second way instead. Either way: same workspace,
        same platform; a mismatch is a 400. Resending a token for an already-warm
        prefix is permitted but yields no additional credit.

        `null` when the refused model isn't eligible for a fallback credit.

      - `fallback_has_prefill_claim: bool`

        Whether the accompanying `fallback_credit_token` may be redeemed with the
        appended-assistant retry form. Only set when `fallback_credit_token` is
        present.

        `true`: retry by resending the same request body plus one appended
        `assistant` message whose content is this response's `content` with any
        trailing whitespace stripped from the final text block and unpaired
        `tool_use` blocks omitted (the same appended-turn shape described on
        `fallback_credit_token`), with the token attached. `false`: retry by
        resending the original request body unchanged, with the token attached —
        the appended-assistant form is not available for this refusal (no
        continuable partial content, or the request uses `output_format` or a
        `tool_choice` that forces tool use). One exception: when the request used
        `output_format` or a forced `tool_choice` and the refusal arrived after
        server tools (including MCP connector tools) had already executed, the
        token may not be redeemable by either retry form; if the exact-body retry
        is then rejected with a 400 saying the token must be redeemed by
        continuing the partial response, discard the token and retry without it.

        Advisory: if an appended-assistant retry is rejected with a 400 despite
        `true`, fall back to resending the original request body with the token.

      - `recommended_model: String`

        The server's suggested retry target for this refusal. Populated when a fallback attempt could not be made (the fallback model's rate limit was exhausted, or it was overloaded); names the fallback model the caller can retry directly. Null otherwise.

      - `type: :refusal`

        - `:refusal`

    - `stop_reason: BetaStopReason`

      The reason that we stopped.

      This may be one the following values:

      * `"end_turn"`: the model reached a natural stopping point
      * `"max_tokens"`: we exceeded the requested `max_tokens` or the model's maximum
      * `"stop_sequence"`: one of your provided custom `stop_sequences` was generated
      * `"tool_use"`: the model invoked one or more tools
      * `"pause_turn"`: we paused a long-running turn. You may provide the response back as-is in a subsequent request to let the model continue.
      * `"refusal"`: when streaming classifiers intervene to handle potential policy violations

      In non-streaming mode this value is always non-null. In streaming mode, it is null in the `message_start` event and non-null otherwise.

      - `:end_turn`

      - `:max_tokens`

      - `:stop_sequence`

      - `:tool_use`

      - `:pause_turn`

      - `:compaction`

      - `:refusal`

      - `:model_context_window_exceeded`

    - `stop_sequence: String`

      Which custom stop sequence was generated, if any.

      This value will be a non-null string if one of your custom stop sequences was generated.

    - `type: :message`

      Object type.

      For Messages, this is always `"message"`.

      - `:message`

    - `usage: BetaUsage`

      Billing and rate-limit usage.

      Anthropic's API bills and rate-limits by token counts, as tokens represent the underlying cost to our systems.

      Under the hood, the API transforms requests into a format suitable for the model. The model's output then goes through a parsing stage before becoming an API response. As a result, the token counts in `usage` will not match one-to-one with the exact visible content of an API request or response.

      For example, `output_tokens` will be non-zero, even for an empty string response from Claude.

      Total input tokens in a request is the summation of `input_tokens`, `cache_creation_input_tokens`, and `cache_read_input_tokens`.

      - `cache_creation: BetaCacheCreation`

        Breakdown of cached tokens by TTL

        - `ephemeral_1h_input_tokens: Integer`

          The number of input tokens used to create the 1 hour cache entry.

        - `ephemeral_5m_input_tokens: Integer`

          The number of input tokens used to create the 5 minute cache entry.

      - `cache_creation_input_tokens: Integer`

        The number of input tokens used to create the cache entry.

      - `cache_read_input_tokens: Integer`

        The number of input tokens read from the cache.

      - `inference_geo: String`

        The geographic region where inference was performed for this request.

      - `input_tokens: Integer`

        The number of input tokens which were used.

      - `iterations: BetaIterationsUsage`

        Per-iteration token usage breakdown.

        Each entry represents one sampling iteration, with its own input/output token counts and cache statistics. This allows you to:

        - Determine which iterations exceeded long context thresholds (>=200k tokens)
        - Calculate the true context window size from the last iteration
        - Understand token accumulation across server-side tool use loops

        - `class BetaMessageIterationUsage`

          Token usage for a sampling iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :message`

            Usage for a sampling iteration

            - `:message`

        - `class BetaCompactionIterationUsage`

          Token usage for a compaction iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :compaction`

            Usage for a compaction iteration

            - `:compaction`

        - `class BetaAdvisorMessageIterationUsage`

          Token usage for an advisor sub-inference iteration.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :advisor_message`

            Usage for an advisor sub-inference iteration

            - `:advisor_message`

        - `class BetaFallbackMessageIterationUsage`

          Token usage for the fallback-model attempt of a server-side fallback request.

          Produced in place of a `message` entry for whichever hop served the
          response. A declined hop produces the existing `message` entry. Whether
          a fallback model served the response is signalled by the presence of this
          entry in `usage.iterations`.

          - `cache_creation: BetaCacheCreation`

            Breakdown of cached tokens by TTL

          - `cache_creation_input_tokens: Integer`

            The number of input tokens used to create the cache entry.

          - `cache_read_input_tokens: Integer`

            The number of input tokens read from the cache.

          - `input_tokens: Integer`

            The number of input tokens which were used.

          - `model: Model`

            The model that will complete your prompt.

            See [models](https://docs.anthropic.com/en/docs/models-overview) for additional details and options.

          - `output_tokens: Integer`

            The number of output tokens which were used.

          - `type: :fallback_message`

            Usage for the fallback-model attempt that served the response

            - `:fallback_message`

      - `output_tokens: Integer`

        The number of output tokens which were used.

      - `output_tokens_details: BetaOutputTokensDetails`

        Breakdown of output tokens by category.

        `output_tokens` remains the inclusive, authoritative total used for billing.
        This object provides a read-only decomposition for observability — for example,
        how many of the billed output tokens were spent on internal reasoning that may
        have been summarized before being returned to you.

        - `thinking_tokens: Integer`

          Number of output tokens the model generated as internal reasoning, including
          the thinking-block delimiter tokens.

          Reflects the raw reasoning the model produced, not the (possibly shorter)
          summarized thinking text returned in the response body. Computed by
          re-tokenizing the raw reasoning text, so it may differ from the model's exact
          generation count by a small number of tokens. Always ≤ `output_tokens`;
          `output_tokens - thinking_tokens` approximates the non-reasoning output.

      - `server_tool_use: BetaServerToolUsage`

        The number of server tool requests.

        - `web_fetch_requests: Integer`

          The number of web fetch tool requests.

        - `web_search_requests: Integer`

          The number of web search tool requests.

      - `service_tier: :standard | :priority | :batch`

        If the request used the priority, standard, or batch tier.

        - `:standard`

        - `:priority`

        - `:batch`

      - `speed: :standard | :fast`

        The inference speed mode used for this request.

        - `:standard`

        - `:fast`

  - `type: :succeeded`

    - `:succeeded`