Anthropic Claude OpenAPI Specification (with PDF beta headers)

schema.yml

openapi: 3.0.3
info:
  title: Anthropics Messages API
  version: 1.0.0
servers:
  - url: https://api.anthropic.com

paths:
  /v1/messages:
    post:
      summary: Send messages and receive a response from the Anthropic model
      description: This endpoint sends one or more messages to the Anthropic model and returns the model's response. Refer to the Anthropics Messages API documentation for more details.
      operationId: sendMessage
      tags:
        - Messages
      parameters:
        - name: anthropic-version
          in: header
          required: true
          schema:
            type: string
            example: "2023-06-01"
          description: Specifies the version of the Anthropic API to use.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - model
                - messages
              properties:
                model:
                  type: string
                  description: The identifier of the model to send messages to.
                  example: "claude-3-5-sonnet-20241022"
                max_tokens:
                  type: integer
                  description: The maximum number of tokens to generate in the response.
                  example: 1024
                messages:
                  type: array
                  description: A list of messages in the conversation so far.
                  items:
                    type: object
                    required:
                      - role
                      - content
                    properties:
                      role:
                        type: string
                        description: The role of the entity sending the message, typically "user" or "assistant".
                        example: "user"
                      content:
                        type: array
                        description: The content of the message. Each element can be text or a document.
                        items:
                          type: object
                          oneOf:
                            - type: object
                              description: A document content block.
                              required:
                                - type
                                - source
                              properties:
                                type:
                                  type: string
                                  description: Indicates this content block is a document.
                                  example: "document"
                                source:
                                  type: object
                                  description: Source information for the document.
                                  required:
                                    - type
                                    - media_type
                                    - data
                                  properties:
                                    type:
                                      type: string
                                      description: The encoding type of the document data.
                                      example: "base64"
                                    media_type:
                                      type: string
                                      description: The MIME type of the document.
                                      example: "application/pdf"
                                    data:
                                      type: string
                                      description: Base64-encoded document data.
                                      example: "$PDF_BASE64"
                                cache_control:
                                  type: object
                                  description: Cache control settings for the document.
                                  properties:
                                    type:
                                      type: string
                                      description: The cache control strategy.
                                      example: "ephemeral"
                            - type: object
                              description: A text content block.
                              required:
                                - type
                                - text
                              properties:
                                type:
                                  type: string
                                  description: Indicates this content block is text.
                                  example: "text"
                                text:
                                  type: string
                                  description: The text content of the message.
                                  example: "Which model has the highest human preference win rates across each use-case?"
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                type: object
                properties:
                  content:
                    type: array
                    description: The assistant's response message content blocks.
                    items:
                      type: object
                      properties:
                        text:
                          type: string
                          description: The text of the assistant's response.
                        type:
                          type: string
                          description: The type of the content block.
                  id:
                    type: string
                    description: The unique identifier of the message.
                  model:
                    type: string
                    description: The model that produced the response.
                  role:
                    type: string
                    description: The role of the message author, typically "assistant".
                  stop_reason:
                    type: string
                    description: The reason the model stopped producing tokens.
                  stop_sequence:
                    type: string
                    nullable: true
                    description: The stop sequence that caused the model to stop, if any.
                  type:
                    type: string
                    description: The type of the returned object, typically "message".
                  usage:
                    type: object
                    description: Information about token usage.
                    properties:
                      input_tokens:
                        type: integer
                        description: The number of input tokens consumed.
                      output_tokens:
                        type: integer
                        description: The number of output tokens produced.
              example:
                content:
                  - text: "Hi! My name is Claude."
                    type: "text"
                id: "msg_013Zva2CMHLNnXjNJJKqJ2EF"
                model: "claude-3-5-sonnet-20241022"
                role: "assistant"
                stop_reason: "end_turn"
                stop_sequence: null
                type: "message"
                usage:
                  input_tokens: 2095
                  output_tokens: 503
        '400':
          description: Bad request - invalid input or parameters.
        '401':
          description: Unauthorized - invalid or missing API key.
        '500':
          description: Internal server error.

Looks like Anthropic still hasn't managed to get an OpenAPI schema up and running, so here's a schema built from their docs.