Claude Models API

openapi: 3.1.0
info:
  title: Claude Messages Message Batches Models API
  description: Anthropic's Claude Messages API for sending messages to Claude models and receiving responses. Includes endpoints for creating messages, counting tokens, managing message batches, and listing available models.
  version: 2023-06-01
  termsOfService: https://www.anthropic.com/legal/commercial-terms
  contact:
    name: Anthropic Support
    url: https://support.anthropic.com
    email: support@anthropic.com
  license:
    name: Anthropic API Terms
    url: https://www.anthropic.com/legal/commercial-terms
servers:
- url: https://api.anthropic.com/v1
  description: Anthropic Production API
security:
- ApiKeyAuth: []
tags:
- name: Models
  description: List and retrieve available Claude models
  externalDocs:
    url: https://docs.anthropic.com/en/api/models-list
paths:
  /models:
    get:
      operationId: listModels
      summary: List Models
      description: List available models. The response can be used to determine which models are available for use in the API. More recently released models are listed first.
      tags:
      - Models
      parameters:
      - $ref: '#/components/parameters/AnthropicVersion'
      - $ref: '#/components/parameters/AnthropicBeta'
      - name: after_id
        in: query
        description: ID of the object to use as a cursor for pagination. Returns the page of results immediately after this object.
        schema:
          type: string
      - name: before_id
        in: query
        description: ID of the object to use as a cursor for pagination. Returns the page of results immediately before this object.
        schema:
          type: string
      - name: limit
        in: query
        description: Number of items to return per page.
        schema:
          type: integer
          default: 20
          minimum: 1
          maximum: 1000
      responses:
        '200':
          description: List of available models
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ModelList'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '429':
          $ref: '#/components/responses/RateLimited'
        '500':
          $ref: '#/components/responses/InternalError'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
  /models/{model_id}:
    get:
      operationId: getModel
      summary: Get a Model
      description: Retrieve metadata for a specific Claude model by its ID.
      tags:
      - Models
      parameters:
      - $ref: '#/components/parameters/AnthropicVersion'
      - $ref: '#/components/parameters/AnthropicBeta'
      - name: model_id
        in: path
        required: true
        description: The unique identifier of the model to retrieve.
        schema:
          type: string
        example: claude-sonnet-4-6
      responses:
        '200':
          description: Model metadata
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ModelInfo'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '429':
          $ref: '#/components/responses/RateLimited'
        '500':
          $ref: '#/components/responses/InternalError'
      x-microcks-operation:
        delay: 0
        dispatcher: FALLBACK
components:
  schemas:
    ModelInfo:
      type: object
      description: Metadata about a Claude model.
      required:
      - id
      - type
      - display_name
      - created_at
      properties:
        id:
          type: string
          description: Unique model identifier.
          example: claude-sonnet-4-6
        type:
          type: string
          description: Object type. Always "model" for model objects.
          const: model
          example: example_value
        display_name:
          type: string
          description: A human-readable name for the model.
          example: Claude Sonnet 4.6
        created_at:
          type: string
          format: date-time
          description: RFC 3339 datetime string representing when the model was released.
          example: '2026-01-15T10:30:00Z'
    ModelList:
      type: object
      description: Paginated list of available models.
      properties:
        data:
          type: array
          items:
            $ref: '#/components/schemas/ModelInfo'
          example: []
        has_more:
          type: boolean
          description: Whether there are more results available.
          example: true
        first_id:
          type: string
          description: ID of the first item. Use as before_id for the previous page.
          nullable: true
          example: '500123'
        last_id:
          type: string
          description: ID of the last item. Use as after_id for the next page.
          nullable: true
          example: '500123'
    Error:
      type: object
      description: An error response from the API.
      required:
      - type
      - error
      properties:
        type:
          type: string
          const: error
          example: example_value
        error:
          type: object
          required:
          - type
          - message
          properties:
            type:
              type: string
              description: The type of error.
              enum:
              - invalid_request_error
              - authentication_error
              - permission_error
              - not_found_error
              - rate_limit_error
              - api_error
              - overloaded_error
            message:
              type: string
              description: A human-readable description of the error.
          example: example_value
  parameters:
    AnthropicBeta:
      name: anthropic-beta
      in: header
      required: false
      description: Optional header to specify beta version(s) you want to use.
      schema:
        type: array
        items:
          type: string
    AnthropicVersion:
      name: anthropic-version
      in: header
      required: true
      description: The version of the Anthropic API to use.
      schema:
        type: string
        default: '2023-06-01'
      example: '2023-06-01'
  responses:
    Unauthorized:
      description: Authentication failed. Verify your API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Rate limit exceeded. Retry after the period indicated in the response headers.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The requested resource was not found.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    InternalError:
      description: An unexpected error occurred on the server.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: API key for authenticating requests. Obtain from the Anthropic Console at https://console.anthropic.com
externalDocs:
  description: Anthropic API Documentation
  url: https://docs.anthropic.com/en/api/messages