Messages
Create a Message
Count tokens in a Message
ModelsExpand Collapse
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class CacheControlEphemeral { type, ttl }
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CacheCreation { ephemeral_1h_input_tokens, ephemeral_5m_input_tokens }
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.
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsConfigParam { enabled }
class CitationsDelta { citation, type }
citation: CitationCharLocation { cited_text, document_index, document_title, 4 more } | CitationPageLocation { cited_text, document_index, document_title, 4 more } | CitationContentBlockLocation { cited_text, document_index, document_title, 4 more } | 2 more
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :citations_delta
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
ContentBlock = TextBlock { citations, text, type } | ThinkingBlock { signature, thinking, type } | RedactedThinkingBlock { data, type } | 3 more
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
ContentBlockParam = TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | DocumentBlockParam { source, type, cache_control, 3 more } | 7 more
Regular text content.
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ThinkingBlockParam { signature, thinking, type }
type: :thinking
class RedactedThinkingBlockParam { data, type }
type: :redacted_thinking
class ToolUseBlockParam { id, input, name, 2 more }
type: :tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolResultBlockParam { tool_use_id, type, cache_control, 2 more }
type: :tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
content: String | Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ServerToolUseBlockParam { id, input, name, 2 more }
name: :web_search
type: :server_tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class WebSearchToolResultBlockParam { content, tool_use_id, type, cache_control }
Array[WebSearchResultBlockParam { encrypted_content, title, type, 2 more } ]
type: :web_search_result
class WebSearchToolRequestError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
type: :web_search_tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
ContentBlockSourceContent = TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control }
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class InputJSONDelta { partial_json, type }
type: :input_json_delta
class Message { id, content, model, 5 more }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.
MessageCountTokensTool = Tool { input_schema, name, cache_control, 2 more } | ToolBash20250124 { name, type, cache_control } | ToolTextEditor20250124 { name, type, cache_control } | 3 more
class Tool { input_schema, name, cache_control, 2 more }
input_schema: { type, properties, required}
JSON schema for this tool's input.
This defines the shape of the input that your tool accepts and that the model will produce.
type: :object
name: String
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
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.
type: :custom
class ToolBash20250124 { name, type, cache_control }
name: :bash
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :bash_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250124 { name, type, cache_control }
name: :str_replace_editor
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :text_editor_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250429 { name, type, cache_control }
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.
type: :text_editor_20250429
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250728 { name, type, cache_control, max_characters }
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.
type: :text_editor_20250728
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_characters: Integer
Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.
class WebSearchTool20250305 { name, type, allowed_domains, 4 more }
name: :web_search
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :web_search_20250305
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.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_uses: Integer
Maximum number of times the tool can be used in the API request.
user_location: { type, city, country, 2 more}
Parameters for the user's location. Used to provide more relevant search results.
type: :approximate
city: String
The city of the user.
country: String
The two letter ISO country code of the user.
region: String
The region of the user.
timezone: String
The IANA timezone of the user.
class MessageDeltaUsage { cache_creation_input_tokens, cache_read_input_tokens, input_tokens, 2 more }
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.
output_tokens: Integer
The cumulative number of output tokens which were used.
The number of server tool requests.
web_search_requests: Integer
The number of web search tool requests.
class MessageParam { content, role }
Array[ContentBlockParam]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ThinkingBlockParam { signature, thinking, type }
type: :thinking
class RedactedThinkingBlockParam { data, type }
type: :redacted_thinking
class ToolUseBlockParam { id, input, name, 2 more }
type: :tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolResultBlockParam { tool_use_id, type, cache_control, 2 more }
type: :tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
content: String | Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ServerToolUseBlockParam { id, input, name, 2 more }
name: :web_search
type: :server_tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class WebSearchToolResultBlockParam { content, tool_use_id, type, cache_control }
Array[WebSearchResultBlockParam { encrypted_content, title, type, 2 more } ]
type: :web_search_result
class WebSearchToolRequestError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
type: :web_search_tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
role: :user | :assistant
class MessageTokensCount { input_tokens }
input_tokens: Integer
The total number of tokens across the provided list of messages, system prompt, and tools.
class Metadata { user_id }
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.
Model = :"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more | String
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
RawContentBlockDelta = TextDelta { text, type } | InputJSONDelta { partial_json, type } | CitationsDelta { citation, type } | 2 more
class TextDelta { text, type }
type: :text_delta
class InputJSONDelta { partial_json, type }
type: :input_json_delta
class CitationsDelta { citation, type }
citation: CitationCharLocation { cited_text, document_index, document_title, 4 more } | CitationPageLocation { cited_text, document_index, document_title, 4 more } | CitationContentBlockLocation { cited_text, document_index, document_title, 4 more } | 2 more
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :citations_delta
class ThinkingDelta { thinking, type }
type: :thinking_delta
class SignatureDelta { signature, type }
type: :signature_delta
class RawContentBlockDeltaEvent { delta, index, type }
class TextDelta { text, type }
type: :text_delta
class InputJSONDelta { partial_json, type }
type: :input_json_delta
class CitationsDelta { citation, type }
citation: CitationCharLocation { cited_text, document_index, document_title, 4 more } | CitationPageLocation { cited_text, document_index, document_title, 4 more } | CitationContentBlockLocation { cited_text, document_index, document_title, 4 more } | 2 more
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :citations_delta
class ThinkingDelta { thinking, type }
type: :thinking_delta
class SignatureDelta { signature, type }
type: :signature_delta
type: :content_block_delta
class RawContentBlockStartEvent { content_block, index, type }
content_block: TextBlock { citations, text, type } | ThinkingBlock { signature, thinking, type } | RedactedThinkingBlock { data, type } | 3 more
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
type: :content_block_start
class RawContentBlockStopEvent { index, type }
type: :content_block_stop
class RawMessageDeltaEvent { delta, type, usage }
delta: { stop_reason, stop_sequence}
type: :message_delta
usage: MessageDeltaUsage { cache_creation_input_tokens, cache_read_input_tokens, input_tokens, 2 more }
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.
output_tokens: Integer
The cumulative number of output tokens which were used.
The number of server tool requests.
web_search_requests: Integer
The number of web search tool requests.
class RawMessageStartEvent { message, type }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.
type: :message_start
class RawMessageStopEvent { type }
type: :message_stop
RawMessageStreamEvent = RawMessageStartEvent { message, type } | RawMessageDeltaEvent { delta, type, usage } | RawMessageStopEvent { type } | 3 more
class RawMessageStartEvent { message, type }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.
type: :message_start
class RawMessageDeltaEvent { delta, type, usage }
delta: { stop_reason, stop_sequence}
type: :message_delta
usage: MessageDeltaUsage { cache_creation_input_tokens, cache_read_input_tokens, input_tokens, 2 more }
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.
output_tokens: Integer
The cumulative number of output tokens which were used.
The number of server tool requests.
web_search_requests: Integer
The number of web search tool requests.
class RawMessageStopEvent { type }
type: :message_stop
class RawContentBlockStartEvent { content_block, index, type }
content_block: TextBlock { citations, text, type } | ThinkingBlock { signature, thinking, type } | RedactedThinkingBlock { data, type } | 3 more
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
type: :content_block_start
class RawContentBlockDeltaEvent { delta, index, type }
class TextDelta { text, type }
type: :text_delta
class InputJSONDelta { partial_json, type }
type: :input_json_delta
class CitationsDelta { citation, type }
citation: CitationCharLocation { cited_text, document_index, document_title, 4 more } | CitationPageLocation { cited_text, document_index, document_title, 4 more } | CitationContentBlockLocation { cited_text, document_index, document_title, 4 more } | 2 more
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :citations_delta
class ThinkingDelta { thinking, type }
type: :thinking_delta
class SignatureDelta { signature, type }
type: :signature_delta
type: :content_block_delta
class RawContentBlockStopEvent { index, type }
type: :content_block_stop
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class RedactedThinkingBlockParam { data, type }
type: :redacted_thinking
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ServerToolUsage { web_search_requests }
web_search_requests: Integer
The number of web search tool requests.
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class ServerToolUseBlockParam { id, input, name, 2 more }
name: :web_search
type: :server_tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SignatureDelta { signature, type }
type: :signature_delta
StopReason = :end_turn | :max_tokens | :stop_sequence | 3 more
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
TextCitation = CitationCharLocation { cited_text, document_index, document_title, 4 more } | CitationPageLocation { cited_text, document_index, document_title, 4 more } | CitationContentBlockLocation { cited_text, document_index, document_title, 4 more } | 2 more
class CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
TextCitationParam = CitationCharLocationParam { cited_text, document_index, document_title, 3 more } | CitationPageLocationParam { cited_text, document_index, document_title, 3 more } | CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more } | 2 more
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class TextDelta { text, type }
type: :text_delta
class ThinkingBlock { signature, thinking, type }
type: :thinking
class ThinkingBlockParam { signature, thinking, type }
type: :thinking
class ThinkingConfigDisabled { type }
type: :disabled
class ThinkingConfigEnabled { budget_tokens, type }
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 for details.
type: :enabled
ThinkingConfigParam = ThinkingConfigEnabled { budget_tokens, type } | ThinkingConfigDisabled { type }
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 for details.
class ThinkingConfigEnabled { budget_tokens, type }
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 for details.
type: :enabled
class ThinkingConfigDisabled { type }
type: :disabled
class ThinkingDelta { thinking, type }
type: :thinking_delta
class Tool { input_schema, name, cache_control, 2 more }
input_schema: { type, properties, required}
JSON schema for this tool's input.
This defines the shape of the input that your tool accepts and that the model will produce.
type: :object
name: String
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
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.
type: :custom
class ToolBash20250124 { name, type, cache_control }
name: :bash
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :bash_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
ToolChoice = ToolChoiceAuto { type, disable_parallel_tool_use } | ToolChoiceAny { type, disable_parallel_tool_use } | ToolChoiceTool { name, type, disable_parallel_tool_use } | ToolChoiceNone { type }
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 ToolChoiceAuto { type, disable_parallel_tool_use }
The model will automatically decide whether to use tools.
type: :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 ToolChoiceAny { type, disable_parallel_tool_use }
The model will use any available tools.
type: :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 ToolChoiceTool { name, type, disable_parallel_tool_use }
The model will use the specified tool with tool_choice.name.
name: String
The name of the tool to use.
type: :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 ToolChoiceNone { type }
The model will not be allowed to use tools.
type: :none
class ToolChoiceAny { type, disable_parallel_tool_use }
The model will use any available tools.
type: :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 ToolChoiceAuto { type, disable_parallel_tool_use }
The model will automatically decide whether to use tools.
type: :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 ToolChoiceNone { type }
The model will not be allowed to use tools.
type: :none
class ToolChoiceTool { name, type, disable_parallel_tool_use }
The model will use the specified tool with tool_choice.name.
name: String
The name of the tool to use.
type: :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 ToolResultBlockParam { tool_use_id, type, cache_control, 2 more }
type: :tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
content: String | Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
Array[TextBlockParam { text, type, cache_control, citations } | ImageBlockParam { source, type, cache_control } | SearchResultBlockParam { content, source, title, 3 more } | DocumentBlockParam { source, type, cache_control, 3 more } ]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class SearchResultBlockParam { content, source, title, 3 more }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :search_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class DocumentBlockParam { source, type, cache_control, 3 more }
source: Base64PDFSource { data, media_type, type } | PlainTextSource { data, media_type, type } | ContentBlockSource { content, type } | URLPDFSource { type, url }
class Base64PDFSource { data, media_type, type }
media_type: :"application/pdf"
type: :base64
class PlainTextSource { data, media_type, type }
media_type: :"text/plain"
type: :text
class ContentBlockSource { content, type }
Array[ContentBlockSourceContent]
class TextBlockParam { text, type, cache_control, citations }
type: :text
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class CitationCharLocationParam { cited_text, document_index, document_title, 3 more }
type: :char_location
class CitationPageLocationParam { cited_text, document_index, document_title, 3 more }
type: :page_location
class CitationContentBlockLocationParam { cited_text, document_index, document_title, 3 more }
type: :content_block_location
class CitationWebSearchResultLocationParam { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationSearchResultLocationParam { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
class ImageBlockParam { source, type, cache_control }
class Base64ImageSource { data, media_type, type }
media_type: :"image/jpeg" | :"image/png" | :"image/gif" | :"image/webp"
type: :base64
class URLImageSource { type, url }
type: :url
type: :image
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
type: :content
class URLPDFSource { type, url }
type: :url
type: :document
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250124 { name, type, cache_control }
name: :str_replace_editor
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :text_editor_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250429 { name, type, cache_control }
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.
type: :text_editor_20250429
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250728 { name, type, cache_control, max_characters }
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.
type: :text_editor_20250728
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_characters: Integer
Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.
ToolUnion = Tool { input_schema, name, cache_control, 2 more } | ToolBash20250124 { name, type, cache_control } | ToolTextEditor20250124 { name, type, cache_control } | 3 more
class Tool { input_schema, name, cache_control, 2 more }
input_schema: { type, properties, required}
JSON schema for this tool's input.
This defines the shape of the input that your tool accepts and that the model will produce.
type: :object
name: String
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
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.
type: :custom
class ToolBash20250124 { name, type, cache_control }
name: :bash
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :bash_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250124 { name, type, cache_control }
name: :str_replace_editor
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :text_editor_20250124
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250429 { name, type, cache_control }
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.
type: :text_editor_20250429
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class ToolTextEditor20250728 { name, type, cache_control, max_characters }
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.
type: :text_editor_20250728
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_characters: Integer
Maximum number of characters to display when viewing a file. If not specified, defaults to displaying the full file.
class WebSearchTool20250305 { name, type, allowed_domains, 4 more }
name: :web_search
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :web_search_20250305
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.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_uses: Integer
Maximum number of times the tool can be used in the API request.
user_location: { type, city, country, 2 more}
Parameters for the user's location. Used to provide more relevant search results.
type: :approximate
city: String
The city of the user.
country: String
The two letter ISO country code of the user.
region: String
The region of the user.
timezone: String
The IANA timezone of the user.
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ToolUseBlockParam { id, input, name, 2 more }
type: :tool_use
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
class URLImageSource { type, url }
type: :url
class URLPDFSource { type, url }
type: :url
class Usage { cache_creation, cache_creation_input_tokens, cache_read_input_tokens, 4 more }
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.
The number of server 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.
class WebSearchResultBlock { encrypted_content, page_age, title, 2 more }
type: :web_search_result
class WebSearchResultBlockParam { encrypted_content, title, type, 2 more }
type: :web_search_result
class WebSearchTool20250305 { name, type, allowed_domains, 4 more }
name: :web_search
Name of the tool.
This is how the tool will be called by the model and in tool_use blocks.
type: :web_search_20250305
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.
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
max_uses: Integer
Maximum number of times the tool can be used in the API request.
user_location: { type, city, country, 2 more}
Parameters for the user's location. Used to provide more relevant search results.
type: :approximate
city: String
The city of the user.
country: String
The two letter ISO country code of the user.
region: String
The region of the user.
timezone: String
The IANA timezone of the user.
class WebSearchToolRequestError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
WebSearchToolResultBlockContent = WebSearchToolResultError { error_code, type } | Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
class WebSearchToolResultBlockParam { content, tool_use_id, type, cache_control }
Array[WebSearchResultBlockParam { encrypted_content, title, type, 2 more } ]
type: :web_search_result
class WebSearchToolRequestError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
type: :web_search_tool_result
Create a cache control breakpoint at this content block.
type: :ephemeral
ttl: :"5m" | :"1h"
The time-to-live for the cache control breakpoint.
This may be one the following values:
5m: 5 minutes1h: 1 hour
Defaults to 5m.
WebSearchToolResultBlockParamContent = Array[WebSearchResultBlockParam { encrypted_content, title, type, 2 more } ] | WebSearchToolRequestError { error_code, type }
Array[WebSearchResultBlockParam { encrypted_content, title, type, 2 more } ]
type: :web_search_result
class WebSearchToolRequestError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
MessagesBatches
Create a Message Batch
Retrieve a Message Batch
List Message Batches
Cancel a Message Batch
Delete a Message Batch
Retrieve Message Batch results
ModelsExpand Collapse
class DeletedMessageBatch { id, type }
id: String
ID of the Message Batch.
type: :message_batch_deleted
Deleted object type.
For Message Batches, this is always "message_batch_deleted".
class MessageBatch { id, archived_at, cancel_initiated_at, 7 more }
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.
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".
class MessageBatchCanceledResult { type }
type: :canceled
class MessageBatchErroredResult { error, type }
class InvalidRequestError { message, type }
type: :invalid_request_error
class AuthenticationError { message, type }
type: :authentication_error
class BillingError { message, type }
type: :billing_error
class PermissionError { message, type }
type: :permission_error
class NotFoundError { message, type }
type: :not_found_error
class RateLimitError { message, type }
type: :rate_limit_error
class GatewayTimeoutError { message, type }
type: :timeout_error
class APIErrorObject { message, type }
type: :api_error
class OverloadedError { message, type }
type: :overloaded_error
type: :error
type: :errored
class MessageBatchExpiredResult { type }
type: :expired
class MessageBatchIndividualResponse { custom_id, result }
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.
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 MessageBatchSucceededResult { message, type }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.
type: :succeeded
class MessageBatchErroredResult { error, type }
class InvalidRequestError { message, type }
type: :invalid_request_error
class AuthenticationError { message, type }
type: :authentication_error
class BillingError { message, type }
type: :billing_error
class PermissionError { message, type }
type: :permission_error
class NotFoundError { message, type }
type: :not_found_error
class RateLimitError { message, type }
type: :rate_limit_error
class GatewayTimeoutError { message, type }
type: :timeout_error
class APIErrorObject { message, type }
type: :api_error
class OverloadedError { message, type }
type: :overloaded_error
type: :error
type: :errored
class MessageBatchCanceledResult { type }
type: :canceled
class MessageBatchExpiredResult { type }
type: :expired
class MessageBatchRequestCounts { canceled, errored, expired, 2 more }
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.
MessageBatchResult = MessageBatchSucceededResult { message, type } | MessageBatchErroredResult { error, type } | MessageBatchCanceledResult { type } | MessageBatchExpiredResult { type }
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 MessageBatchSucceededResult { message, type }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.
type: :succeeded
class MessageBatchErroredResult { error, type }
class InvalidRequestError { message, type }
type: :invalid_request_error
class AuthenticationError { message, type }
type: :authentication_error
class BillingError { message, type }
type: :billing_error
class PermissionError { message, type }
type: :permission_error
class NotFoundError { message, type }
type: :not_found_error
class RateLimitError { message, type }
type: :rate_limit_error
class GatewayTimeoutError { message, type }
type: :timeout_error
class APIErrorObject { message, type }
type: :api_error
class OverloadedError { message, type }
type: :overloaded_error
type: :error
type: :errored
class MessageBatchCanceledResult { type }
type: :canceled
class MessageBatchExpiredResult { type }
type: :expired
class MessageBatchSucceededResult { message, type }
id: String
Unique object identifier.
The format and length of IDs may change over time.
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)"}]
class TextBlock { citations, text, type }
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 CitationCharLocation { cited_text, document_index, document_title, 4 more }
type: :char_location
class CitationPageLocation { cited_text, document_index, document_title, 4 more }
type: :page_location
class CitationContentBlockLocation { cited_text, document_index, document_title, 4 more }
type: :content_block_location
class CitationsWebSearchResultLocation { cited_text, encrypted_index, title, 2 more }
type: :web_search_result_location
class CitationsSearchResultLocation { cited_text, end_block_index, search_result_index, 4 more }
type: :search_result_location
type: :text
class ThinkingBlock { signature, thinking, type }
type: :thinking
class RedactedThinkingBlock { data, type }
type: :redacted_thinking
class ToolUseBlock { id, input, name, type }
type: :tool_use
class ServerToolUseBlock { id, input, name, type }
name: :web_search
type: :server_tool_use
class WebSearchToolResultBlock { content, tool_use_id, type }
class WebSearchToolResultError { error_code, type }
error_code: :invalid_tool_input | :unavailable | :max_uses_exceeded | 2 more
type: :web_search_tool_result_error
Array[WebSearchResultBlock { encrypted_content, page_age, title, 2 more } ]
type: :web_search_result
type: :web_search_tool_result
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101" | :"claude-opus-4-5" | :"claude-3-7-sonnet-latest" | 17 more
The model that will complete your prompt.
See models for additional details and options.
:"claude-opus-4-5-20251101"
Premium model combining maximum intelligence with practical performance
:"claude-opus-4-5"
Premium model combining maximum intelligence with practical performance
:"claude-3-7-sonnet-latest"
High-performance model with early extended thinking
:"claude-3-7-sonnet-20250219"
High-performance model with early extended thinking
:"claude-3-5-haiku-latest"
Fastest and most compact model for near-instant responsiveness
:"claude-3-5-haiku-20241022"
Our fastest model
:"claude-haiku-4-5"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-haiku-4-5-20251001"
Hybrid model, capable of near-instant responses and extended thinking
:"claude-sonnet-4-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-0"
High-performance model with extended thinking
:"claude-4-sonnet-20250514"
High-performance model with extended thinking
:"claude-sonnet-4-5"
Our best model for real-world agents and coding
:"claude-sonnet-4-5-20250929"
Our best model for real-world agents and coding
:"claude-opus-4-0"
Our most capable model
:"claude-opus-4-20250514"
Our most capable model
:"claude-4-opus-20250514"
Our most capable model
:"claude-opus-4-1-20250805"
Our most capable model
:"claude-3-opus-latest"
Excels at writing and complex tasks
:"claude-3-opus-20240229"
Excels at writing and complex tasks
:"claude-3-haiku-20240307"
Our previous most fast and cost-effective
role: :assistant
Conversational role of the generated message.
This will always be "assistant".
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 requestedmax_tokensor the model's maximum"stop_sequence": one of your provided customstop_sequenceswas 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.
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".
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.
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.
The number of server 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.