Batches

Create a Message Batch

client.Beta.Messages.Batches.New(ctx, params) (*BetaMessageBatch, error)

POST/v1/messages/batches

Retrieve a Message Batch

client.Beta.Messages.Batches.Get(ctx, messageBatchID, query) (*BetaMessageBatch, error)

GET/v1/messages/batches/{message_batch_id}

List Message Batches

client.Beta.Messages.Batches.List(ctx, params) (*Page[BetaMessageBatch], error)

GET/v1/messages/batches

Cancel a Message Batch

client.Beta.Messages.Batches.Cancel(ctx, messageBatchID, body) (*BetaMessageBatch, error)

POST/v1/messages/batches/{message_batch_id}/cancel

Delete a Message Batch

client.Beta.Messages.Batches.Delete(ctx, messageBatchID, body) (*BetaDeletedMessageBatch, error)

DELETE/v1/messages/batches/{message_batch_id}

Retrieve Message Batch results

client.Beta.Messages.Batches.Results(ctx, messageBatchID, query) (*BetaMessageBatchIndividualResponse, error)

GET/v1/messages/batches/{message_batch_id}/results

ModelsExpand Collapse

type BetaDeletedMessageBatch struct{…}

ID string

ID of the Message Batch.

Type MessageBatchDeleted

Deleted object type.

For Message Batches, this is always "message_batch_deleted".

type BetaMessageBatch struct{…}

ID string

Unique object identifier.

The format and length of IDs may change over time.

ArchivedAt Time

RFC 3339 datetime string representing the time at which the Message Batch was archived and its results became unavailable.

CancelInitiatedAt Time

RFC 3339 datetime string representing the time at which cancellation was initiated for the Message Batch. Specified only if cancellation was initiated.

CreatedAt Time

RFC 3339 datetime string representing the time at which the Message Batch was created.

EndedAt 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.

formatdate-time

ExpiresAt Time

RFC 3339 datetime string representing the time at which the Message Batch will expire and end processing, which is 24 hours after creation.

ProcessingStatus BetaMessageBatchProcessingStatus

Processing status of the Message Batch.

Accepts one of the following:

const BetaMessageBatchProcessingStatusInProgress BetaMessageBatchProcessingStatus = "in_progress"

const BetaMessageBatchProcessingStatusCanceling BetaMessageBatchProcessingStatus = "canceling"

const BetaMessageBatchProcessingStatusEnded BetaMessageBatchProcessingStatus = "ended"

RequestCounts 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 int64

Number of requests in the Message Batch that have been canceled.

This is zero until processing of the entire Message Batch has ended.

Errored int64

Number of requests in the Message Batch that encountered an error.

This is zero until processing of the entire Message Batch has ended.

Expired int64

Number of requests in the Message Batch that have expired.

This is zero until processing of the entire Message Batch has ended.

Processing int64

Number of requests in the Message Batch that are processing.

Succeeded int64

Number of requests in the Message Batch that have completed successfully.

This is zero until processing of the entire Message Batch has ended.

ResultsURL 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 MessageBatch

Object type.

For Message Batches, this is always "message_batch".

type BetaMessageBatchCanceledResult struct{…}

Type Canceled

type BetaMessageBatchErroredResult struct{…}

Error BetaErrorResponse

Error BetaErrorUnion

Accepts one of the following:

type BetaInvalidRequestError struct{…}

Message string

Type InvalidRequestError

type BetaAuthenticationError struct{…}

Message string

Type AuthenticationError

type BetaBillingError struct{…}

Message string

Type BillingError

type BetaPermissionError struct{…}

Message string

Type PermissionError

type BetaNotFoundError struct{…}

Message string

Type NotFoundError

type BetaRateLimitError struct{…}

Message string

Type RateLimitError

type BetaGatewayTimeoutError struct{…}

Message string

Type TimeoutError

type BetaAPIError struct{…}

Message string

Type APIError

type BetaOverloadedError struct{…}

Message string

Type OverloadedError

RequestID string

Type Error

Type Errored

type BetaMessageBatchExpiredResult struct{…}

Type Expired

type BetaMessageBatchIndividualResponse struct{…}

This is a single line in the response .jsonl file and does not represent the response as a whole.

CustomID 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 BetaMessageBatchResultUnion

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.

Accepts one of the following:

type BetaMessageBatchSucceededResult struct{…}

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

ExpiresAt Time

The time at which the container will expire.

Skills []BetaSkill

Skills loaded in the container

SkillID string

Skill ID

Type BetaSkillType

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

Accepts one of the following:

const BetaSkillTypeAnthropic BetaSkillType = "anthropic"

const BetaSkillTypeCustom BetaSkillType = "custom"

Version string

Skill version or 'latest' for most recent version

Content []BetaContentBlockUnion

Content generated by the model.

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

Example:

[{"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:

[
  {"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:

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

Accepts one of the following:

type BetaTextBlock struct{…}

Citations []BetaTextCitationUnion

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.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

type BetaThinkingBlock struct{…}

Signature string

Thinking string

Type Thinking

type BetaRedactedThinkingBlock struct{…}

Data string

Type RedactedThinking

type BetaToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

Type ToolUse

Caller BetaToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaServerToolUseBlock struct{…}

ID string

Input map[string, any]

Name BetaServerToolUseBlockName

Accepts one of the following:

const BetaServerToolUseBlockNameWebSearch BetaServerToolUseBlockName = "web_search"

const BetaServerToolUseBlockNameWebFetch BetaServerToolUseBlockName = "web_fetch"

const BetaServerToolUseBlockNameCodeExecution BetaServerToolUseBlockName = "code_execution"

const BetaServerToolUseBlockNameBashCodeExecution BetaServerToolUseBlockName = "bash_code_execution"

const BetaServerToolUseBlockNameTextEditorCodeExecution BetaServerToolUseBlockName = "text_editor_code_execution"

const BetaServerToolUseBlockNameToolSearchToolRegex BetaServerToolUseBlockName = "tool_search_tool_regex"

const BetaServerToolUseBlockNameToolSearchToolBm25 BetaServerToolUseBlockName = "tool_search_tool_bm25"

Type ServerToolUse

Caller BetaServerToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebSearchToolResultBlock struct{…}

Content BetaWebSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebSearchToolResultError struct{…}

ErrorCode BetaWebSearchToolResultErrorCode

Accepts one of the following:

const BetaWebSearchToolResultErrorCodeInvalidToolInput BetaWebSearchToolResultErrorCode = "invalid_tool_input"

const BetaWebSearchToolResultErrorCodeUnavailable BetaWebSearchToolResultErrorCode = "unavailable"

const BetaWebSearchToolResultErrorCodeMaxUsesExceeded BetaWebSearchToolResultErrorCode = "max_uses_exceeded"

const BetaWebSearchToolResultErrorCodeTooManyRequests BetaWebSearchToolResultErrorCode = "too_many_requests"

const BetaWebSearchToolResultErrorCodeQueryTooLong BetaWebSearchToolResultErrorCode = "query_too_long"

const BetaWebSearchToolResultErrorCodeRequestTooLarge BetaWebSearchToolResultErrorCode = "request_too_large"

Type WebSearchToolResultError

type BetaWebSearchToolResultBlockContentArray []BetaWebSearchResultBlock

EncryptedContent string

PageAge string

Title string

Type WebSearchResult

URL string

ToolUseID string

Type WebSearchToolResult

Caller BetaWebSearchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebFetchToolResultBlock struct{…}

Content BetaWebFetchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebFetchToolResultErrorBlock struct{…}

ErrorCode BetaWebFetchToolResultErrorCode

Accepts one of the following:

const BetaWebFetchToolResultErrorCodeInvalidToolInput BetaWebFetchToolResultErrorCode = "invalid_tool_input"

const BetaWebFetchToolResultErrorCodeURLTooLong BetaWebFetchToolResultErrorCode = "url_too_long"

const BetaWebFetchToolResultErrorCodeURLNotAllowed BetaWebFetchToolResultErrorCode = "url_not_allowed"

const BetaWebFetchToolResultErrorCodeURLNotAccessible BetaWebFetchToolResultErrorCode = "url_not_accessible"

const BetaWebFetchToolResultErrorCodeUnsupportedContentType BetaWebFetchToolResultErrorCode = "unsupported_content_type"

const BetaWebFetchToolResultErrorCodeTooManyRequests BetaWebFetchToolResultErrorCode = "too_many_requests"

const BetaWebFetchToolResultErrorCodeMaxUsesExceeded BetaWebFetchToolResultErrorCode = "max_uses_exceeded"

const BetaWebFetchToolResultErrorCodeUnavailable BetaWebFetchToolResultErrorCode = "unavailable"

Type WebFetchToolResultError

type BetaWebFetchBlock struct{…}

Content BetaDocumentBlock

Citations BetaCitationConfig

Citation configuration for the document

Enabled bool

Source BetaDocumentBlockSourceUnion

Accepts one of the following:

type BetaBase64PDFSource struct{…}

Data string

MediaType ApplicationPDF

Type Base64

type BetaPlainTextSource struct{…}

Data string

MediaType TextPlain

Type Text

Title string

The title of the document

Type Document

RetrievedAt string

ISO 8601 timestamp when the content was retrieved

Type WebFetchResult

URL string

Fetched content URL

ToolUseID string

Type WebFetchToolResult

Caller BetaWebFetchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaCodeExecutionToolResultBlock struct{…}

Content BetaCodeExecutionToolResultBlockContentUnion

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

Accepts one of the following:

type BetaCodeExecutionToolResultError struct{…}

ErrorCode BetaCodeExecutionToolResultErrorCode

Accepts one of the following:

const BetaCodeExecutionToolResultErrorCodeInvalidToolInput BetaCodeExecutionToolResultErrorCode = "invalid_tool_input"

const BetaCodeExecutionToolResultErrorCodeUnavailable BetaCodeExecutionToolResultErrorCode = "unavailable"

const BetaCodeExecutionToolResultErrorCodeTooManyRequests BetaCodeExecutionToolResultErrorCode = "too_many_requests"

const BetaCodeExecutionToolResultErrorCodeExecutionTimeExceeded BetaCodeExecutionToolResultErrorCode = "execution_time_exceeded"

Type CodeExecutionToolResultError

type BetaCodeExecutionResultBlock struct{…}

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type CodeExecutionResult

type BetaEncryptedCodeExecutionResultBlock struct{…}

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

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

EncryptedStdout string

ReturnCode int64

Stderr string

Type EncryptedCodeExecutionResult

ToolUseID string

Type CodeExecutionToolResult

type BetaBashCodeExecutionToolResultBlock struct{…}

Content BetaBashCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaBashCodeExecutionToolResultError struct{…}

ErrorCode BetaBashCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaBashCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaBashCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaBashCodeExecutionToolResultErrorErrorCodeUnavailable BetaBashCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaBashCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaBashCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaBashCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaBashCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaBashCodeExecutionToolResultErrorErrorCodeOutputFileTooLarge BetaBashCodeExecutionToolResultErrorErrorCode = "output_file_too_large"

Type BashCodeExecutionToolResultError

type BetaBashCodeExecutionResultBlock struct{…}

Content []BetaBashCodeExecutionOutputBlock

FileID string

Type BashCodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type BashCodeExecutionResult

ToolUseID string

Type BashCodeExecutionToolResult

type BetaTextEditorCodeExecutionToolResultBlock struct{…}

Content BetaTextEditorCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaTextEditorCodeExecutionToolResultError struct{…}

ErrorCode BetaTextEditorCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaTextEditorCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeUnavailable BetaTextEditorCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaTextEditorCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaTextEditorCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeFileNotFound BetaTextEditorCodeExecutionToolResultErrorErrorCode = "file_not_found"

ErrorMessage string

Type TextEditorCodeExecutionToolResultError

type BetaTextEditorCodeExecutionViewResultBlock struct{…}

Content string

FileType BetaTextEditorCodeExecutionViewResultBlockFileType

Accepts one of the following:

const BetaTextEditorCodeExecutionViewResultBlockFileTypeText BetaTextEditorCodeExecutionViewResultBlockFileType = "text"

const BetaTextEditorCodeExecutionViewResultBlockFileTypeImage BetaTextEditorCodeExecutionViewResultBlockFileType = "image"

const BetaTextEditorCodeExecutionViewResultBlockFileTypePDF BetaTextEditorCodeExecutionViewResultBlockFileType = "pdf"

NumLines int64

StartLine int64

TotalLines int64

Type TextEditorCodeExecutionViewResult

type BetaTextEditorCodeExecutionCreateResultBlock struct{…}

IsFileUpdate bool

Type TextEditorCodeExecutionCreateResult

type BetaTextEditorCodeExecutionStrReplaceResultBlock struct{…}

Lines []string

NewLines int64

NewStart int64

OldLines int64

OldStart int64

Type TextEditorCodeExecutionStrReplaceResult

ToolUseID string

Type TextEditorCodeExecutionToolResult

type BetaToolSearchToolResultBlock struct{…}

Content BetaToolSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaToolSearchToolResultError struct{…}

ErrorCode BetaToolSearchToolResultErrorErrorCode

Accepts one of the following:

const BetaToolSearchToolResultErrorErrorCodeInvalidToolInput BetaToolSearchToolResultErrorErrorCode = "invalid_tool_input"

const BetaToolSearchToolResultErrorErrorCodeUnavailable BetaToolSearchToolResultErrorErrorCode = "unavailable"

const BetaToolSearchToolResultErrorErrorCodeTooManyRequests BetaToolSearchToolResultErrorErrorCode = "too_many_requests"

const BetaToolSearchToolResultErrorErrorCodeExecutionTimeExceeded BetaToolSearchToolResultErrorErrorCode = "execution_time_exceeded"

ErrorMessage string

Type ToolSearchToolResultError

type BetaToolSearchToolSearchResultBlock struct{…}

ToolReferences []BetaToolReferenceBlock

ToolName string

Type ToolReference

Type ToolSearchToolSearchResult

ToolUseID string

Type ToolSearchToolResult

type BetaMCPToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

The name of the MCP tool

ServerName string

The name of the MCP server

Type MCPToolUse

type BetaMCPToolResultBlock struct{…}

Content BetaMCPToolResultBlockContentUnion

Accepts one of the following:

string

type BetaMCPToolResultBlockContentBetaMCPToolResultBlockContent []BetaTextBlock

Citations []BetaTextCitationUnion

Citations supporting the text block.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

IsError bool

ToolUseID string

Type MCPToolResult

type BetaContainerUploadBlock struct{…}

Response model for a file uploaded to the container.

FileID string

Type ContainerUpload

type BetaCompactionBlock struct{…}

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

Type Compaction

ContextManagement BetaContextManagementResponse

Context management response.

Information about context management strategies applied during the request.

AppliedEdits []BetaContextManagementResponseAppliedEditUnion

List of context management edits that were applied.

Accepts one of the following:

type BetaClearToolUses20250919EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedToolUses int64

Number of tool uses that were cleared.

Type ClearToolUses20250919

The type of context management edit applied.

type BetaClearThinking20251015EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedThinkingTurns int64

Number of thinking turns that were cleared.

Type ClearThinking20251015

The type of context management edit applied.

Model Model

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

type Model string

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

const ModelClaudeOpus4_6 Model = "claude-opus-4-6"

Most intelligent model for building agents and coding

const ModelClaudeSonnet4_6 Model = "claude-sonnet-4-6"

Frontier intelligence at scale — built for coding, agents, and enterprise workflows

const ModelClaudeOpus4_5_20251101 Model = "claude-opus-4-5-20251101"

Premium model combining maximum intelligence with practical performance

const ModelClaudeOpus4_5 Model = "claude-opus-4-5"

Premium model combining maximum intelligence with practical performance

const ModelClaude3_7SonnetLatest Model = "claude-3-7-sonnet-latest"

High-performance model with early extended thinking

const ModelClaude3_7Sonnet20250219 Model = "claude-3-7-sonnet-20250219"

High-performance model with early extended thinking

const ModelClaude3_5HaikuLatest Model = "claude-3-5-haiku-latest"

Fastest and most compact model for near-instant responsiveness

const ModelClaude3_5Haiku20241022 Model = "claude-3-5-haiku-20241022"

Our fastest model

const ModelClaudeHaiku4_5 Model = "claude-haiku-4-5"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeHaiku4_5_20251001 Model = "claude-haiku-4-5-20251001"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeSonnet4_20250514 Model = "claude-sonnet-4-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_0 Model = "claude-sonnet-4-0"

High-performance model with extended thinking

const ModelClaude4Sonnet20250514 Model = "claude-4-sonnet-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_5 Model = "claude-sonnet-4-5"

Our best model for real-world agents and coding

const ModelClaudeSonnet4_5_20250929 Model = "claude-sonnet-4-5-20250929"

Our best model for real-world agents and coding

const ModelClaudeOpus4_0 Model = "claude-opus-4-0"

Our most capable model

const ModelClaudeOpus4_20250514 Model = "claude-opus-4-20250514"

Our most capable model

const ModelClaude4Opus20250514 Model = "claude-4-opus-20250514"

Our most capable model

const ModelClaudeOpus4_1_20250805 Model = "claude-opus-4-1-20250805"

Our most capable model

const ModelClaude3OpusLatest Model = "claude-3-opus-latest"

Excels at writing and complex tasks

const ModelClaude_3_Opus_20240229 Model = "claude-3-opus-20240229"

Excels at writing and complex tasks

const ModelClaude_3_Haiku_20240307 Model = "claude-3-haiku-20240307"

Our previous most fast and cost-effective

string

Role Assistant

Conversational role of the generated message.

This will always be "assistant".

StopReason 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.

Accepts one of the following:

const BetaStopReasonEndTurn BetaStopReason = "end_turn"

const BetaStopReasonMaxTokens BetaStopReason = "max_tokens"

const BetaStopReasonStopSequence BetaStopReason = "stop_sequence"

const BetaStopReasonToolUse BetaStopReason = "tool_use"

const BetaStopReasonPauseTurn BetaStopReason = "pause_turn"

const BetaStopReasonCompaction BetaStopReason = "compaction"

const BetaStopReasonRefusal BetaStopReason = "refusal"

const BetaStopReasonModelContextWindowExceeded BetaStopReason = "model_context_window_exceeded"

StopSequence 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".

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.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InferenceGeo string

The geographic region where inference was performed for this request.

InputTokens int64

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

Accepts one of the following:

type BetaMessageIterationUsage struct{…}

Token usage for a sampling iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Message

Usage for a sampling iteration

type BetaCompactionIterationUsage struct{…}

Token usage for a compaction iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Compaction

Usage for a compaction iteration

OutputTokens int64

The number of output tokens which were used.

ServerToolUse BetaServerToolUsage

The number of server tool requests.

WebFetchRequests int64

The number of web fetch tool requests.

WebSearchRequests int64

The number of web search tool requests.

ServiceTier BetaUsageServiceTier

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

Accepts one of the following:

const BetaUsageServiceTierStandard BetaUsageServiceTier = "standard"

const BetaUsageServiceTierPriority BetaUsageServiceTier = "priority"

const BetaUsageServiceTierBatch BetaUsageServiceTier = "batch"

Speed BetaUsageSpeed

The inference speed mode used for this request.

Accepts one of the following:

const BetaUsageSpeedStandard BetaUsageSpeed = "standard"

const BetaUsageSpeedFast BetaUsageSpeed = "fast"

Type Succeeded

type BetaMessageBatchErroredResult struct{…}

Error BetaErrorResponse

Error BetaErrorUnion

Accepts one of the following:

type BetaInvalidRequestError struct{…}

Message string

Type InvalidRequestError

type BetaAuthenticationError struct{…}

Message string

Type AuthenticationError

type BetaBillingError struct{…}

Message string

Type BillingError

type BetaPermissionError struct{…}

Message string

Type PermissionError

type BetaNotFoundError struct{…}

Message string

Type NotFoundError

type BetaRateLimitError struct{…}

Message string

Type RateLimitError

type BetaGatewayTimeoutError struct{…}

Message string

Type TimeoutError

type BetaAPIError struct{…}

Message string

Type APIError

type BetaOverloadedError struct{…}

Message string

Type OverloadedError

RequestID string

Type Error

Type Errored

type BetaMessageBatchCanceledResult struct{…}

Type Canceled

type BetaMessageBatchExpiredResult struct{…}

Type Expired

type BetaMessageBatchRequestCounts struct{…}

Canceled int64

Number of requests in the Message Batch that have been canceled.

This is zero until processing of the entire Message Batch has ended.

Errored int64

Number of requests in the Message Batch that encountered an error.

This is zero until processing of the entire Message Batch has ended.

Expired int64

Number of requests in the Message Batch that have expired.

This is zero until processing of the entire Message Batch has ended.

Processing int64

Number of requests in the Message Batch that are processing.

Succeeded int64

Number of requests in the Message Batch that have completed successfully.

This is zero until processing of the entire Message Batch has ended.

type BetaMessageBatchResultUnion interface{…}

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.

Accepts one of the following:

type BetaMessageBatchSucceededResult struct{…}

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

ExpiresAt Time

The time at which the container will expire.

Skills []BetaSkill

Skills loaded in the container

SkillID string

Skill ID

Type BetaSkillType

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

Accepts one of the following:

const BetaSkillTypeAnthropic BetaSkillType = "anthropic"

const BetaSkillTypeCustom BetaSkillType = "custom"

Version string

Skill version or 'latest' for most recent version

Content []BetaContentBlockUnion

Content generated by the model.

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

Example:

[{"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:

[
  {"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:

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

Accepts one of the following:

type BetaTextBlock struct{…}

Citations []BetaTextCitationUnion

Citations supporting the text block.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

type BetaThinkingBlock struct{…}

Signature string

Thinking string

Type Thinking

type BetaRedactedThinkingBlock struct{…}

Data string

Type RedactedThinking

type BetaToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

Type ToolUse

Caller BetaToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaServerToolUseBlock struct{…}

ID string

Input map[string, any]

Name BetaServerToolUseBlockName

Accepts one of the following:

const BetaServerToolUseBlockNameWebSearch BetaServerToolUseBlockName = "web_search"

const BetaServerToolUseBlockNameWebFetch BetaServerToolUseBlockName = "web_fetch"

const BetaServerToolUseBlockNameCodeExecution BetaServerToolUseBlockName = "code_execution"

const BetaServerToolUseBlockNameBashCodeExecution BetaServerToolUseBlockName = "bash_code_execution"

const BetaServerToolUseBlockNameTextEditorCodeExecution BetaServerToolUseBlockName = "text_editor_code_execution"

const BetaServerToolUseBlockNameToolSearchToolRegex BetaServerToolUseBlockName = "tool_search_tool_regex"

const BetaServerToolUseBlockNameToolSearchToolBm25 BetaServerToolUseBlockName = "tool_search_tool_bm25"

Type ServerToolUse

Caller BetaServerToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebSearchToolResultBlock struct{…}

Content BetaWebSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebSearchToolResultError struct{…}

ErrorCode BetaWebSearchToolResultErrorCode

Accepts one of the following:

const BetaWebSearchToolResultErrorCodeInvalidToolInput BetaWebSearchToolResultErrorCode = "invalid_tool_input"

const BetaWebSearchToolResultErrorCodeUnavailable BetaWebSearchToolResultErrorCode = "unavailable"

const BetaWebSearchToolResultErrorCodeMaxUsesExceeded BetaWebSearchToolResultErrorCode = "max_uses_exceeded"

const BetaWebSearchToolResultErrorCodeTooManyRequests BetaWebSearchToolResultErrorCode = "too_many_requests"

const BetaWebSearchToolResultErrorCodeQueryTooLong BetaWebSearchToolResultErrorCode = "query_too_long"

const BetaWebSearchToolResultErrorCodeRequestTooLarge BetaWebSearchToolResultErrorCode = "request_too_large"

Type WebSearchToolResultError

type BetaWebSearchToolResultBlockContentArray []BetaWebSearchResultBlock

EncryptedContent string

PageAge string

Title string

Type WebSearchResult

URL string

ToolUseID string

Type WebSearchToolResult

Caller BetaWebSearchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebFetchToolResultBlock struct{…}

Content BetaWebFetchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebFetchToolResultErrorBlock struct{…}

ErrorCode BetaWebFetchToolResultErrorCode

Accepts one of the following:

const BetaWebFetchToolResultErrorCodeInvalidToolInput BetaWebFetchToolResultErrorCode = "invalid_tool_input"

const BetaWebFetchToolResultErrorCodeURLTooLong BetaWebFetchToolResultErrorCode = "url_too_long"

const BetaWebFetchToolResultErrorCodeURLNotAllowed BetaWebFetchToolResultErrorCode = "url_not_allowed"

const BetaWebFetchToolResultErrorCodeURLNotAccessible BetaWebFetchToolResultErrorCode = "url_not_accessible"

const BetaWebFetchToolResultErrorCodeUnsupportedContentType BetaWebFetchToolResultErrorCode = "unsupported_content_type"

const BetaWebFetchToolResultErrorCodeTooManyRequests BetaWebFetchToolResultErrorCode = "too_many_requests"

const BetaWebFetchToolResultErrorCodeMaxUsesExceeded BetaWebFetchToolResultErrorCode = "max_uses_exceeded"

const BetaWebFetchToolResultErrorCodeUnavailable BetaWebFetchToolResultErrorCode = "unavailable"

Type WebFetchToolResultError

type BetaWebFetchBlock struct{…}

Content BetaDocumentBlock

Citations BetaCitationConfig

Citation configuration for the document

Enabled bool

Source BetaDocumentBlockSourceUnion

Accepts one of the following:

type BetaBase64PDFSource struct{…}

Data string

MediaType ApplicationPDF

Type Base64

type BetaPlainTextSource struct{…}

Data string

MediaType TextPlain

Type Text

Title string

The title of the document

Type Document

RetrievedAt string

ISO 8601 timestamp when the content was retrieved

Type WebFetchResult

URL string

Fetched content URL

ToolUseID string

Type WebFetchToolResult

Caller BetaWebFetchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaCodeExecutionToolResultBlock struct{…}

Content BetaCodeExecutionToolResultBlockContentUnion

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

Accepts one of the following:

type BetaCodeExecutionToolResultError struct{…}

ErrorCode BetaCodeExecutionToolResultErrorCode

Accepts one of the following:

const BetaCodeExecutionToolResultErrorCodeInvalidToolInput BetaCodeExecutionToolResultErrorCode = "invalid_tool_input"

const BetaCodeExecutionToolResultErrorCodeUnavailable BetaCodeExecutionToolResultErrorCode = "unavailable"

const BetaCodeExecutionToolResultErrorCodeTooManyRequests BetaCodeExecutionToolResultErrorCode = "too_many_requests"

const BetaCodeExecutionToolResultErrorCodeExecutionTimeExceeded BetaCodeExecutionToolResultErrorCode = "execution_time_exceeded"

Type CodeExecutionToolResultError

type BetaCodeExecutionResultBlock struct{…}

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type CodeExecutionResult

type BetaEncryptedCodeExecutionResultBlock struct{…}

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

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

EncryptedStdout string

ReturnCode int64

Stderr string

Type EncryptedCodeExecutionResult

ToolUseID string

Type CodeExecutionToolResult

type BetaBashCodeExecutionToolResultBlock struct{…}

Content BetaBashCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaBashCodeExecutionToolResultError struct{…}

ErrorCode BetaBashCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaBashCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaBashCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaBashCodeExecutionToolResultErrorErrorCodeUnavailable BetaBashCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaBashCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaBashCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaBashCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaBashCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaBashCodeExecutionToolResultErrorErrorCodeOutputFileTooLarge BetaBashCodeExecutionToolResultErrorErrorCode = "output_file_too_large"

Type BashCodeExecutionToolResultError

type BetaBashCodeExecutionResultBlock struct{…}

Content []BetaBashCodeExecutionOutputBlock

FileID string

Type BashCodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type BashCodeExecutionResult

ToolUseID string

Type BashCodeExecutionToolResult

type BetaTextEditorCodeExecutionToolResultBlock struct{…}

Content BetaTextEditorCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaTextEditorCodeExecutionToolResultError struct{…}

ErrorCode BetaTextEditorCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaTextEditorCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeUnavailable BetaTextEditorCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaTextEditorCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaTextEditorCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeFileNotFound BetaTextEditorCodeExecutionToolResultErrorErrorCode = "file_not_found"

ErrorMessage string

Type TextEditorCodeExecutionToolResultError

type BetaTextEditorCodeExecutionViewResultBlock struct{…}

Content string

FileType BetaTextEditorCodeExecutionViewResultBlockFileType

Accepts one of the following:

const BetaTextEditorCodeExecutionViewResultBlockFileTypeText BetaTextEditorCodeExecutionViewResultBlockFileType = "text"

const BetaTextEditorCodeExecutionViewResultBlockFileTypeImage BetaTextEditorCodeExecutionViewResultBlockFileType = "image"

const BetaTextEditorCodeExecutionViewResultBlockFileTypePDF BetaTextEditorCodeExecutionViewResultBlockFileType = "pdf"

NumLines int64

StartLine int64

TotalLines int64

Type TextEditorCodeExecutionViewResult

type BetaTextEditorCodeExecutionCreateResultBlock struct{…}

IsFileUpdate bool

Type TextEditorCodeExecutionCreateResult

type BetaTextEditorCodeExecutionStrReplaceResultBlock struct{…}

Lines []string

NewLines int64

NewStart int64

OldLines int64

OldStart int64

Type TextEditorCodeExecutionStrReplaceResult

ToolUseID string

Type TextEditorCodeExecutionToolResult

type BetaToolSearchToolResultBlock struct{…}

Content BetaToolSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaToolSearchToolResultError struct{…}

ErrorCode BetaToolSearchToolResultErrorErrorCode

Accepts one of the following:

const BetaToolSearchToolResultErrorErrorCodeInvalidToolInput BetaToolSearchToolResultErrorErrorCode = "invalid_tool_input"

const BetaToolSearchToolResultErrorErrorCodeUnavailable BetaToolSearchToolResultErrorErrorCode = "unavailable"

const BetaToolSearchToolResultErrorErrorCodeTooManyRequests BetaToolSearchToolResultErrorErrorCode = "too_many_requests"

const BetaToolSearchToolResultErrorErrorCodeExecutionTimeExceeded BetaToolSearchToolResultErrorErrorCode = "execution_time_exceeded"

ErrorMessage string

Type ToolSearchToolResultError

type BetaToolSearchToolSearchResultBlock struct{…}

ToolReferences []BetaToolReferenceBlock

ToolName string

Type ToolReference

Type ToolSearchToolSearchResult

ToolUseID string

Type ToolSearchToolResult

type BetaMCPToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

The name of the MCP tool

ServerName string

The name of the MCP server

Type MCPToolUse

type BetaMCPToolResultBlock struct{…}

Content BetaMCPToolResultBlockContentUnion

Accepts one of the following:

string

type BetaMCPToolResultBlockContentBetaMCPToolResultBlockContent []BetaTextBlock

Citations []BetaTextCitationUnion

Citations supporting the text block.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

IsError bool

ToolUseID string

Type MCPToolResult

type BetaContainerUploadBlock struct{…}

Response model for a file uploaded to the container.

FileID string

Type ContainerUpload

type BetaCompactionBlock struct{…}

A compaction block returned when autocompact is triggered.

Content string

Summary of compacted content, or null if compaction failed

Type Compaction

ContextManagement BetaContextManagementResponse

Context management response.

Information about context management strategies applied during the request.

AppliedEdits []BetaContextManagementResponseAppliedEditUnion

List of context management edits that were applied.

Accepts one of the following:

type BetaClearToolUses20250919EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedToolUses int64

Number of tool uses that were cleared.

Type ClearToolUses20250919

The type of context management edit applied.

type BetaClearThinking20251015EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedThinkingTurns int64

Number of thinking turns that were cleared.

Type ClearThinking20251015

The type of context management edit applied.

Model Model

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

type Model string

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

const ModelClaudeOpus4_6 Model = "claude-opus-4-6"

Most intelligent model for building agents and coding

const ModelClaudeSonnet4_6 Model = "claude-sonnet-4-6"

Frontier intelligence at scale — built for coding, agents, and enterprise workflows

const ModelClaudeOpus4_5_20251101 Model = "claude-opus-4-5-20251101"

Premium model combining maximum intelligence with practical performance

const ModelClaudeOpus4_5 Model = "claude-opus-4-5"

Premium model combining maximum intelligence with practical performance

const ModelClaude3_7SonnetLatest Model = "claude-3-7-sonnet-latest"

High-performance model with early extended thinking

const ModelClaude3_7Sonnet20250219 Model = "claude-3-7-sonnet-20250219"

High-performance model with early extended thinking

const ModelClaude3_5HaikuLatest Model = "claude-3-5-haiku-latest"

Fastest and most compact model for near-instant responsiveness

const ModelClaude3_5Haiku20241022 Model = "claude-3-5-haiku-20241022"

Our fastest model

const ModelClaudeHaiku4_5 Model = "claude-haiku-4-5"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeHaiku4_5_20251001 Model = "claude-haiku-4-5-20251001"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeSonnet4_20250514 Model = "claude-sonnet-4-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_0 Model = "claude-sonnet-4-0"

High-performance model with extended thinking

const ModelClaude4Sonnet20250514 Model = "claude-4-sonnet-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_5 Model = "claude-sonnet-4-5"

Our best model for real-world agents and coding

const ModelClaudeSonnet4_5_20250929 Model = "claude-sonnet-4-5-20250929"

Our best model for real-world agents and coding

const ModelClaudeOpus4_0 Model = "claude-opus-4-0"

Our most capable model

const ModelClaudeOpus4_20250514 Model = "claude-opus-4-20250514"

Our most capable model

const ModelClaude4Opus20250514 Model = "claude-4-opus-20250514"

Our most capable model

const ModelClaudeOpus4_1_20250805 Model = "claude-opus-4-1-20250805"

Our most capable model

const ModelClaude3OpusLatest Model = "claude-3-opus-latest"

Excels at writing and complex tasks

const ModelClaude_3_Opus_20240229 Model = "claude-3-opus-20240229"

Excels at writing and complex tasks

const ModelClaude_3_Haiku_20240307 Model = "claude-3-haiku-20240307"

Our previous most fast and cost-effective

string

Role Assistant

Conversational role of the generated message.

This will always be "assistant".

StopReason 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.

Accepts one of the following:

const BetaStopReasonEndTurn BetaStopReason = "end_turn"

const BetaStopReasonMaxTokens BetaStopReason = "max_tokens"

const BetaStopReasonStopSequence BetaStopReason = "stop_sequence"

const BetaStopReasonToolUse BetaStopReason = "tool_use"

const BetaStopReasonPauseTurn BetaStopReason = "pause_turn"

const BetaStopReasonCompaction BetaStopReason = "compaction"

const BetaStopReasonRefusal BetaStopReason = "refusal"

const BetaStopReasonModelContextWindowExceeded BetaStopReason = "model_context_window_exceeded"

StopSequence 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".

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.

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.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InferenceGeo string

The geographic region where inference was performed for this request.

InputTokens int64

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

Accepts one of the following:

type BetaMessageIterationUsage struct{…}

Token usage for a sampling iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Message

Usage for a sampling iteration

type BetaCompactionIterationUsage struct{…}

Token usage for a compaction iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Compaction

Usage for a compaction iteration

OutputTokens int64

The number of output tokens which were used.

ServerToolUse BetaServerToolUsage

The number of server tool requests.

WebFetchRequests int64

The number of web fetch tool requests.

WebSearchRequests int64

The number of web search tool requests.

ServiceTier BetaUsageServiceTier

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

Accepts one of the following:

const BetaUsageServiceTierStandard BetaUsageServiceTier = "standard"

const BetaUsageServiceTierPriority BetaUsageServiceTier = "priority"

const BetaUsageServiceTierBatch BetaUsageServiceTier = "batch"

Speed BetaUsageSpeed

The inference speed mode used for this request.

Accepts one of the following:

const BetaUsageSpeedStandard BetaUsageSpeed = "standard"

const BetaUsageSpeedFast BetaUsageSpeed = "fast"

Type Succeeded

type BetaMessageBatchErroredResult struct{…}

Error BetaErrorResponse

Error BetaErrorUnion

Accepts one of the following:

type BetaInvalidRequestError struct{…}

Message string

Type InvalidRequestError

type BetaAuthenticationError struct{…}

Message string

Type AuthenticationError

type BetaBillingError struct{…}

Message string

Type BillingError

type BetaPermissionError struct{…}

Message string

Type PermissionError

type BetaNotFoundError struct{…}

Message string

Type NotFoundError

type BetaRateLimitError struct{…}

Message string

Type RateLimitError

type BetaGatewayTimeoutError struct{…}

Message string

Type TimeoutError

type BetaAPIError struct{…}

Message string

Type APIError

type BetaOverloadedError struct{…}

Message string

Type OverloadedError

RequestID string

Type Error

Type Errored

type BetaMessageBatchCanceledResult struct{…}

Type Canceled

type BetaMessageBatchExpiredResult struct{…}

Type Expired

type BetaMessageBatchSucceededResult struct{…}

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

ExpiresAt Time

The time at which the container will expire.

Skills []BetaSkill

Skills loaded in the container

SkillID string

Skill ID

Type BetaSkillType

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

Accepts one of the following:

const BetaSkillTypeAnthropic BetaSkillType = "anthropic"

const BetaSkillTypeCustom BetaSkillType = "custom"

Version string

Skill version or 'latest' for most recent version

Content []BetaContentBlockUnion

Content generated by the model.

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

Example:

[{"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:

[
  {"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:

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

Accepts one of the following:

type BetaTextBlock struct{…}

Citations []BetaTextCitationUnion

Citations supporting the text block.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

type BetaThinkingBlock struct{…}

Signature string

Thinking string

Type Thinking

type BetaRedactedThinkingBlock struct{…}

Data string

Type RedactedThinking

type BetaToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

Type ToolUse

Caller BetaToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaServerToolUseBlock struct{…}

ID string

Input map[string, any]

Name BetaServerToolUseBlockName

Accepts one of the following:

const BetaServerToolUseBlockNameWebSearch BetaServerToolUseBlockName = "web_search"

const BetaServerToolUseBlockNameWebFetch BetaServerToolUseBlockName = "web_fetch"

const BetaServerToolUseBlockNameCodeExecution BetaServerToolUseBlockName = "code_execution"

const BetaServerToolUseBlockNameBashCodeExecution BetaServerToolUseBlockName = "bash_code_execution"

const BetaServerToolUseBlockNameTextEditorCodeExecution BetaServerToolUseBlockName = "text_editor_code_execution"

const BetaServerToolUseBlockNameToolSearchToolRegex BetaServerToolUseBlockName = "tool_search_tool_regex"

const BetaServerToolUseBlockNameToolSearchToolBm25 BetaServerToolUseBlockName = "tool_search_tool_bm25"

Type ServerToolUse

Caller BetaServerToolUseBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebSearchToolResultBlock struct{…}

Content BetaWebSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebSearchToolResultError struct{…}

ErrorCode BetaWebSearchToolResultErrorCode

Accepts one of the following:

const BetaWebSearchToolResultErrorCodeInvalidToolInput BetaWebSearchToolResultErrorCode = "invalid_tool_input"

const BetaWebSearchToolResultErrorCodeUnavailable BetaWebSearchToolResultErrorCode = "unavailable"

const BetaWebSearchToolResultErrorCodeMaxUsesExceeded BetaWebSearchToolResultErrorCode = "max_uses_exceeded"

const BetaWebSearchToolResultErrorCodeTooManyRequests BetaWebSearchToolResultErrorCode = "too_many_requests"

const BetaWebSearchToolResultErrorCodeQueryTooLong BetaWebSearchToolResultErrorCode = "query_too_long"

const BetaWebSearchToolResultErrorCodeRequestTooLarge BetaWebSearchToolResultErrorCode = "request_too_large"

Type WebSearchToolResultError

type BetaWebSearchToolResultBlockContentArray []BetaWebSearchResultBlock

EncryptedContent string

PageAge string

Title string

Type WebSearchResult

URL string

ToolUseID string

Type WebSearchToolResult

Caller BetaWebSearchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaWebFetchToolResultBlock struct{…}

Content BetaWebFetchToolResultBlockContentUnion

Accepts one of the following:

type BetaWebFetchToolResultErrorBlock struct{…}

ErrorCode BetaWebFetchToolResultErrorCode

Accepts one of the following:

const BetaWebFetchToolResultErrorCodeInvalidToolInput BetaWebFetchToolResultErrorCode = "invalid_tool_input"

const BetaWebFetchToolResultErrorCodeURLTooLong BetaWebFetchToolResultErrorCode = "url_too_long"

const BetaWebFetchToolResultErrorCodeURLNotAllowed BetaWebFetchToolResultErrorCode = "url_not_allowed"

const BetaWebFetchToolResultErrorCodeURLNotAccessible BetaWebFetchToolResultErrorCode = "url_not_accessible"

const BetaWebFetchToolResultErrorCodeUnsupportedContentType BetaWebFetchToolResultErrorCode = "unsupported_content_type"

const BetaWebFetchToolResultErrorCodeTooManyRequests BetaWebFetchToolResultErrorCode = "too_many_requests"

const BetaWebFetchToolResultErrorCodeMaxUsesExceeded BetaWebFetchToolResultErrorCode = "max_uses_exceeded"

const BetaWebFetchToolResultErrorCodeUnavailable BetaWebFetchToolResultErrorCode = "unavailable"

Type WebFetchToolResultError

type BetaWebFetchBlock struct{…}

Content BetaDocumentBlock

Citations BetaCitationConfig

Citation configuration for the document

Enabled bool

Source BetaDocumentBlockSourceUnion

Accepts one of the following:

type BetaBase64PDFSource struct{…}

Data string

MediaType ApplicationPDF

Type Base64

type BetaPlainTextSource struct{…}

Data string

MediaType TextPlain

Type Text

Title string

The title of the document

Type Document

RetrievedAt string

ISO 8601 timestamp when the content was retrieved

Type WebFetchResult

URL string

Fetched content URL

ToolUseID string

Type WebFetchToolResult

Caller BetaWebFetchToolResultBlockCallerUnionoptional

Tool invocation directly from the model.

Accepts one of the following:

type BetaDirectCaller struct{…}

Tool invocation directly from the model.

Type Direct

type BetaServerToolCaller struct{…}

Tool invocation generated by a server-side tool.

ToolID string

Type CodeExecution20250825

type BetaServerToolCaller20260120 struct{…}

ToolID string

Type CodeExecution20260120

type BetaCodeExecutionToolResultBlock struct{…}

Content BetaCodeExecutionToolResultBlockContentUnion

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

Accepts one of the following:

type BetaCodeExecutionToolResultError struct{…}

ErrorCode BetaCodeExecutionToolResultErrorCode

Accepts one of the following:

const BetaCodeExecutionToolResultErrorCodeInvalidToolInput BetaCodeExecutionToolResultErrorCode = "invalid_tool_input"

const BetaCodeExecutionToolResultErrorCodeUnavailable BetaCodeExecutionToolResultErrorCode = "unavailable"

const BetaCodeExecutionToolResultErrorCodeTooManyRequests BetaCodeExecutionToolResultErrorCode = "too_many_requests"

const BetaCodeExecutionToolResultErrorCodeExecutionTimeExceeded BetaCodeExecutionToolResultErrorCode = "execution_time_exceeded"

Type CodeExecutionToolResultError

type BetaCodeExecutionResultBlock struct{…}

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type CodeExecutionResult

type BetaEncryptedCodeExecutionResultBlock struct{…}

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

Content []BetaCodeExecutionOutputBlock

FileID string

Type CodeExecutionOutput

EncryptedStdout string

ReturnCode int64

Stderr string

Type EncryptedCodeExecutionResult

ToolUseID string

Type CodeExecutionToolResult

type BetaBashCodeExecutionToolResultBlock struct{…}

Content BetaBashCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaBashCodeExecutionToolResultError struct{…}

ErrorCode BetaBashCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaBashCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaBashCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaBashCodeExecutionToolResultErrorErrorCodeUnavailable BetaBashCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaBashCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaBashCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaBashCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaBashCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaBashCodeExecutionToolResultErrorErrorCodeOutputFileTooLarge BetaBashCodeExecutionToolResultErrorErrorCode = "output_file_too_large"

Type BashCodeExecutionToolResultError

type BetaBashCodeExecutionResultBlock struct{…}

Content []BetaBashCodeExecutionOutputBlock

FileID string

Type BashCodeExecutionOutput

ReturnCode int64

Stderr string

Stdout string

Type BashCodeExecutionResult

ToolUseID string

Type BashCodeExecutionToolResult

type BetaTextEditorCodeExecutionToolResultBlock struct{…}

Content BetaTextEditorCodeExecutionToolResultBlockContentUnion

Accepts one of the following:

type BetaTextEditorCodeExecutionToolResultError struct{…}

ErrorCode BetaTextEditorCodeExecutionToolResultErrorErrorCode

Accepts one of the following:

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeInvalidToolInput BetaTextEditorCodeExecutionToolResultErrorErrorCode = "invalid_tool_input"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeUnavailable BetaTextEditorCodeExecutionToolResultErrorErrorCode = "unavailable"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeTooManyRequests BetaTextEditorCodeExecutionToolResultErrorErrorCode = "too_many_requests"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeExecutionTimeExceeded BetaTextEditorCodeExecutionToolResultErrorErrorCode = "execution_time_exceeded"

const BetaTextEditorCodeExecutionToolResultErrorErrorCodeFileNotFound BetaTextEditorCodeExecutionToolResultErrorErrorCode = "file_not_found"

ErrorMessage string

Type TextEditorCodeExecutionToolResultError

type BetaTextEditorCodeExecutionViewResultBlock struct{…}

Content string

FileType BetaTextEditorCodeExecutionViewResultBlockFileType

Accepts one of the following:

const BetaTextEditorCodeExecutionViewResultBlockFileTypeText BetaTextEditorCodeExecutionViewResultBlockFileType = "text"

const BetaTextEditorCodeExecutionViewResultBlockFileTypeImage BetaTextEditorCodeExecutionViewResultBlockFileType = "image"

const BetaTextEditorCodeExecutionViewResultBlockFileTypePDF BetaTextEditorCodeExecutionViewResultBlockFileType = "pdf"

NumLines int64

StartLine int64

TotalLines int64

Type TextEditorCodeExecutionViewResult

type BetaTextEditorCodeExecutionCreateResultBlock struct{…}

IsFileUpdate bool

Type TextEditorCodeExecutionCreateResult

type BetaTextEditorCodeExecutionStrReplaceResultBlock struct{…}

Lines []string

NewLines int64

NewStart int64

OldLines int64

OldStart int64

Type TextEditorCodeExecutionStrReplaceResult

ToolUseID string

Type TextEditorCodeExecutionToolResult

type BetaToolSearchToolResultBlock struct{…}

Content BetaToolSearchToolResultBlockContentUnion

Accepts one of the following:

type BetaToolSearchToolResultError struct{…}

ErrorCode BetaToolSearchToolResultErrorErrorCode

Accepts one of the following:

const BetaToolSearchToolResultErrorErrorCodeInvalidToolInput BetaToolSearchToolResultErrorErrorCode = "invalid_tool_input"

const BetaToolSearchToolResultErrorErrorCodeUnavailable BetaToolSearchToolResultErrorErrorCode = "unavailable"

const BetaToolSearchToolResultErrorErrorCodeTooManyRequests BetaToolSearchToolResultErrorErrorCode = "too_many_requests"

const BetaToolSearchToolResultErrorErrorCodeExecutionTimeExceeded BetaToolSearchToolResultErrorErrorCode = "execution_time_exceeded"

ErrorMessage string

Type ToolSearchToolResultError

type BetaToolSearchToolSearchResultBlock struct{…}

ToolReferences []BetaToolReferenceBlock

ToolName string

Type ToolReference

Type ToolSearchToolSearchResult

ToolUseID string

Type ToolSearchToolResult

type BetaMCPToolUseBlock struct{…}

ID string

Input map[string, any]

Name string

The name of the MCP tool

ServerName string

The name of the MCP server

Type MCPToolUse

type BetaMCPToolResultBlock struct{…}

Content BetaMCPToolResultBlockContentUnion

Accepts one of the following:

string

type BetaMCPToolResultBlockContentBetaMCPToolResultBlockContent []BetaTextBlock

Citations []BetaTextCitationUnion

Citations supporting the text block.

Accepts one of the following:

type BetaCitationCharLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndCharIndex int64

FileID string

StartCharIndex int64

Type CharLocation

type BetaCitationPageLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndPageNumber int64

FileID string

StartPageNumber int64

Type PageLocation

type BetaCitationContentBlockLocation struct{…}

CitedText string

DocumentIndex int64

DocumentTitle string

EndBlockIndex int64

FileID string

StartBlockIndex int64

Type ContentBlockLocation

type BetaCitationsWebSearchResultLocation struct{…}

CitedText string

EncryptedIndex string

Title string

Type WebSearchResultLocation

URL string

type BetaCitationSearchResultLocation struct{…}

CitedText string

EndBlockIndex int64

SearchResultIndex int64

Source string

StartBlockIndex int64

Title string

Type SearchResultLocation

Text string

Type Text

IsError bool

ToolUseID string

Type MCPToolResult

type BetaContainerUploadBlock struct{…}

Response model for a file uploaded to the container.

FileID string

Type ContainerUpload

type BetaCompactionBlock struct{…}

A compaction block returned when autocompact is triggered.

Content string

Summary of compacted content, or null if compaction failed

Type Compaction

ContextManagement BetaContextManagementResponse

Context management response.

Information about context management strategies applied during the request.

AppliedEdits []BetaContextManagementResponseAppliedEditUnion

List of context management edits that were applied.

Accepts one of the following:

type BetaClearToolUses20250919EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedToolUses int64

Number of tool uses that were cleared.

Type ClearToolUses20250919

The type of context management edit applied.

type BetaClearThinking20251015EditResponse struct{…}

ClearedInputTokens int64

Number of input tokens cleared by this edit.

ClearedThinkingTurns int64

Number of thinking turns that were cleared.

Type ClearThinking20251015

The type of context management edit applied.

Model Model

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

type Model string

The model that will complete your prompt.

See models for additional details and options.

Accepts one of the following:

const ModelClaudeOpus4_6 Model = "claude-opus-4-6"

Most intelligent model for building agents and coding

const ModelClaudeSonnet4_6 Model = "claude-sonnet-4-6"

Frontier intelligence at scale — built for coding, agents, and enterprise workflows

const ModelClaudeOpus4_5_20251101 Model = "claude-opus-4-5-20251101"

Premium model combining maximum intelligence with practical performance

const ModelClaudeOpus4_5 Model = "claude-opus-4-5"

Premium model combining maximum intelligence with practical performance

const ModelClaude3_7SonnetLatest Model = "claude-3-7-sonnet-latest"

High-performance model with early extended thinking

const ModelClaude3_7Sonnet20250219 Model = "claude-3-7-sonnet-20250219"

High-performance model with early extended thinking

const ModelClaude3_5HaikuLatest Model = "claude-3-5-haiku-latest"

Fastest and most compact model for near-instant responsiveness

const ModelClaude3_5Haiku20241022 Model = "claude-3-5-haiku-20241022"

Our fastest model

const ModelClaudeHaiku4_5 Model = "claude-haiku-4-5"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeHaiku4_5_20251001 Model = "claude-haiku-4-5-20251001"

Hybrid model, capable of near-instant responses and extended thinking

const ModelClaudeSonnet4_20250514 Model = "claude-sonnet-4-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_0 Model = "claude-sonnet-4-0"

High-performance model with extended thinking

const ModelClaude4Sonnet20250514 Model = "claude-4-sonnet-20250514"

High-performance model with extended thinking

const ModelClaudeSonnet4_5 Model = "claude-sonnet-4-5"

Our best model for real-world agents and coding

const ModelClaudeSonnet4_5_20250929 Model = "claude-sonnet-4-5-20250929"

Our best model for real-world agents and coding

const ModelClaudeOpus4_0 Model = "claude-opus-4-0"

Our most capable model

const ModelClaudeOpus4_20250514 Model = "claude-opus-4-20250514"

Our most capable model

const ModelClaude4Opus20250514 Model = "claude-4-opus-20250514"

Our most capable model

const ModelClaudeOpus4_1_20250805 Model = "claude-opus-4-1-20250805"

Our most capable model

const ModelClaude3OpusLatest Model = "claude-3-opus-latest"

Excels at writing and complex tasks

const ModelClaude_3_Opus_20240229 Model = "claude-3-opus-20240229"

Excels at writing and complex tasks

const ModelClaude_3_Haiku_20240307 Model = "claude-3-haiku-20240307"

Our previous most fast and cost-effective

string

Role Assistant

Conversational role of the generated message.

This will always be "assistant".

StopReason 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.

Accepts one of the following:

const BetaStopReasonEndTurn BetaStopReason = "end_turn"

const BetaStopReasonMaxTokens BetaStopReason = "max_tokens"

const BetaStopReasonStopSequence BetaStopReason = "stop_sequence"

const BetaStopReasonToolUse BetaStopReason = "tool_use"

const BetaStopReasonPauseTurn BetaStopReason = "pause_turn"

const BetaStopReasonCompaction BetaStopReason = "compaction"

const BetaStopReasonRefusal BetaStopReason = "refusal"

const BetaStopReasonModelContextWindowExceeded BetaStopReason = "model_context_window_exceeded"

StopSequence 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".

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.

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.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InferenceGeo string

The geographic region where inference was performed for this request.

InputTokens int64

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

Accepts one of the following:

type BetaMessageIterationUsage struct{…}

Token usage for a sampling iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Message

Usage for a sampling iteration

type BetaCompactionIterationUsage struct{…}

Token usage for a compaction iteration.

CacheCreation BetaCacheCreation

Breakdown of cached tokens by TTL

Ephemeral1hInputTokens int64

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

Ephemeral5mInputTokens int64

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

CacheCreationInputTokens int64

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

CacheReadInputTokens int64

The number of input tokens read from the cache.

InputTokens int64

The number of input tokens which were used.

OutputTokens int64

The number of output tokens which were used.

Type Compaction

Usage for a compaction iteration

OutputTokens int64

The number of output tokens which were used.

ServerToolUse BetaServerToolUsage

The number of server tool requests.

WebFetchRequests int64

The number of web fetch tool requests.

WebSearchRequests int64

The number of web search tool requests.

ServiceTier BetaUsageServiceTier

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

Accepts one of the following:

const BetaUsageServiceTierStandard BetaUsageServiceTier = "standard"

const BetaUsageServiceTierPriority BetaUsageServiceTier = "priority"

const BetaUsageServiceTierBatch BetaUsageServiceTier = "batch"

Speed BetaUsageSpeed

The inference speed mode used for this request.

Accepts one of the following:

const BetaUsageSpeedStandard BetaUsageSpeed = "standard"

const BetaUsageSpeedFast BetaUsageSpeed = "fast"

Type Succeeded