{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://api.anthropic.com/schemas/claude-message-schema.json",
  "title": "Claude Message",
  "description": "Schema for Anthropic Claude Messages API request and response objects including messages, content blocks, and usage tracking.",
  "type": "object",
  "$defs": {
    "CreateMessageRequest": {
      "type": "object",
      "title": "Create Message Request",
      "description": "Request body for creating a new message with Claude.",
      "required": ["model", "max_tokens", "messages"],
      "properties": {
        "model": {
          "type": "string",
          "description": "The model that will complete your prompt. See the list of available models.",
          "examples": [
            "claude-opus-4-6",
            "claude-sonnet-4-6",
            "claude-sonnet-4-5-20250929",
            "claude-3-5-haiku-latest"
          ]
        },
        "max_tokens": {
          "type": "integer",
          "description": "The maximum number of tokens to generate before stopping. Different models support different maximum values.",
          "minimum": 1,
          "examples": [1024, 4096, 8192]
        },
        "messages": {
          "type": "array",
          "description": "Input messages with alternating user and assistant conversational turns. Maximum 100,000 messages per request.",
          "items": {
            "$ref": "#/$defs/MessageParam"
          },
          "minItems": 1
        },
        "system": {
          "description": "System prompt providing context and instructions to Claude. Can be a string or array of text content blocks.",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "type": "array",
              "items": {
                "$ref": "#/$defs/TextBlockParam"
              }
            }
          ]
        },
        "temperature": {
          "type": "number",
          "description": "Amount of randomness injected into the response. Use closer to 0.0 for analytical tasks, closer to 1.0 for creative tasks.",
          "minimum": 0.0,
          "maximum": 1.0,
          "default": 1.0
        },
        "top_p": {
          "type": "number",
          "description": "Use nucleus sampling. Recommended to use either temperature or top_p, but not both.",
          "minimum": 0.0,
          "maximum": 1.0
        },
        "top_k": {
          "type": "integer",
          "description": "Only sample from the top K options for each subsequent token.",
          "minimum": 1
        },
        "stop_sequences": {
          "type": "array",
          "description": "Custom text sequences that will cause the model to stop generating.",
          "items": {
            "type": "string"
          }
        },
        "stream": {
          "type": "boolean",
          "description": "Whether to incrementally stream the response using server-sent events.",
          "default": false
        },
        "metadata": {
          "$ref": "#/$defs/Metadata"
        },
        "tools": {
          "type": "array",
          "description": "Definitions of tools that the model may use.",
          "items": {
            "$ref": "#/$defs/ToolDefinition"
          }
        },
        "tool_choice": {
          "$ref": "#/$defs/ToolChoice"
        },
        "thinking": {
          "$ref": "#/$defs/ThinkingConfig"
        },
        "output_config": {
          "$ref": "#/$defs/OutputConfig"
        },
        "service_tier": {
          "type": "string",
          "description": "Service tier to use for this request.",
          "enum": ["auto", "standard_only"],
          "default": "auto"
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "Message": {
      "type": "object",
      "title": "Message Response",
      "description": "A message response from Claude.",
      "required": ["id", "type", "role", "content", "model", "stop_reason", "usage"],
      "properties": {
        "id": {
          "type": "string",
          "description": "Unique object identifier for the message.",
          "pattern": "^msg_",
          "examples": ["msg_01XFDUDYJgAACzvnptvVoYEL"]
        },
        "type": {
          "type": "string",
          "description": "Object type. Always 'message' for message responses.",
          "const": "message"
        },
        "role": {
          "type": "string",
          "description": "Conversational role of the generated message. Always 'assistant'.",
          "const": "assistant"
        },
        "content": {
          "type": "array",
          "description": "Content generated by the model. Array of content blocks.",
          "items": {
            "$ref": "#/$defs/ResponseContentBlock"
          }
        },
        "model": {
          "type": "string",
          "description": "The model that handled the request.",
          "examples": ["claude-sonnet-4-6", "claude-opus-4-6"]
        },
        "stop_reason": {
          "type": ["string", "null"],
          "description": "The reason the model stopped generating tokens.",
          "enum": ["end_turn", "max_tokens", "stop_sequence", "tool_use", null]
        },
        "stop_sequence": {
          "type": ["string", "null"],
          "description": "The stop sequence that caused the model to stop, if applicable."
        },
        "usage": {
          "$ref": "#/$defs/Usage"
        }
      },
      "additionalProperties": false
    },
    "MessageParam": {
      "type": "object",
      "title": "Message Parameter",
      "description": "An input message in the conversation.",
      "required": ["role", "content"],
      "properties": {
        "role": {
          "type": "string",
          "description": "The role of the message author.",
          "enum": ["user", "assistant"]
        },
        "content": {
          "description": "The content of the message. Can be a string or array of content blocks.",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "type": "array",
              "items": {
                "$ref": "#/$defs/RequestContentBlock"
              }
            }
          ]
        }
      },
      "additionalProperties": false
    },
    "ResponseContentBlock": {
      "title": "Response Content Block",
      "description": "A content block in a message response from Claude.",
      "oneOf": [
        { "$ref": "#/$defs/TextBlock" },
        { "$ref": "#/$defs/ToolUseBlock" },
        { "$ref": "#/$defs/ThinkingBlock" }
      ]
    },
    "RequestContentBlock": {
      "title": "Request Content Block",
      "description": "A content block in a message request.",
      "oneOf": [
        { "$ref": "#/$defs/TextBlockParam" },
        { "$ref": "#/$defs/ImageBlockParam" },
        { "$ref": "#/$defs/DocumentBlockParam" },
        { "$ref": "#/$defs/ToolUseBlockParam" },
        { "$ref": "#/$defs/ToolResultBlockParam" },
        { "$ref": "#/$defs/ThinkingBlockParam" }
      ]
    },
    "TextBlock": {
      "type": "object",
      "title": "Text Block",
      "description": "A text content block in a response.",
      "required": ["type", "text"],
      "properties": {
        "type": {
          "type": "string",
          "const": "text"
        },
        "text": {
          "type": "string",
          "description": "The generated text content."
        },
        "citations": {
          "type": "array",
          "description": "Citations for the text content, if any.",
          "items": {
            "type": "object"
          }
        }
      },
      "additionalProperties": false
    },
    "TextBlockParam": {
      "type": "object",
      "title": "Text Block Parameter",
      "description": "A text content block in a request.",
      "required": ["type", "text"],
      "properties": {
        "type": {
          "type": "string",
          "const": "text"
        },
        "text": {
          "type": "string",
          "description": "The text content."
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "ImageBlockParam": {
      "type": "object",
      "title": "Image Block Parameter",
      "description": "An image content block supporting base64-encoded or URL-referenced images.",
      "required": ["type", "source"],
      "properties": {
        "type": {
          "type": "string",
          "const": "image"
        },
        "source": {
          "type": "object",
          "description": "The source of the image.",
          "required": ["type"],
          "properties": {
            "type": {
              "type": "string",
              "enum": ["base64", "url"]
            },
            "media_type": {
              "type": "string",
              "description": "The media type of the image.",
              "enum": ["image/jpeg", "image/png", "image/gif", "image/webp"]
            },
            "data": {
              "type": "string",
              "description": "Base64-encoded image data. Required when type is base64."
            },
            "url": {
              "type": "string",
              "format": "uri",
              "description": "URL of the image. Required when type is url."
            }
          }
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "DocumentBlockParam": {
      "type": "object",
      "title": "Document Block Parameter",
      "description": "A document content block for PDFs and text documents.",
      "required": ["type", "source"],
      "properties": {
        "type": {
          "type": "string",
          "const": "document"
        },
        "source": {
          "type": "object",
          "description": "The source of the document.",
          "required": ["type"],
          "properties": {
            "type": {
              "type": "string",
              "enum": ["base64", "url", "text", "content"]
            },
            "media_type": {
              "type": "string",
              "enum": ["application/pdf", "text/plain"]
            },
            "data": {
              "type": "string",
              "description": "Base64-encoded document data."
            },
            "url": {
              "type": "string",
              "format": "uri",
              "description": "URL of the document."
            }
          }
        },
        "title": {
          "type": "string",
          "description": "Optional title for the document."
        },
        "context": {
          "type": "string",
          "description": "Optional context about the document."
        },
        "citations": {
          "type": "object",
          "properties": {
            "enabled": {
              "type": "boolean"
            }
          }
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "ToolUseBlock": {
      "type": "object",
      "title": "Tool Use Block",
      "description": "A tool use content block in a response indicating the model wants to invoke a tool.",
      "required": ["type", "id", "name", "input"],
      "properties": {
        "type": {
          "type": "string",
          "const": "tool_use"
        },
        "id": {
          "type": "string",
          "description": "A unique identifier for this tool use block.",
          "pattern": "^toolu_",
          "examples": ["toolu_01D7FLrfh4GYq7yT1ULFeyMV"]
        },
        "name": {
          "type": "string",
          "description": "The name of the tool being used."
        },
        "input": {
          "type": "object",
          "description": "The input passed to the tool, conforming to the tool's input_schema.",
          "additionalProperties": true
        }
      },
      "additionalProperties": false
    },
    "ToolUseBlockParam": {
      "type": "object",
      "title": "Tool Use Block Parameter",
      "description": "A tool use content block in a request for multi-turn tool use conversations.",
      "required": ["type", "id", "name", "input"],
      "properties": {
        "type": {
          "type": "string",
          "const": "tool_use"
        },
        "id": {
          "type": "string",
          "description": "The unique identifier for this tool use."
        },
        "name": {
          "type": "string",
          "description": "The name of the tool."
        },
        "input": {
          "type": "object",
          "description": "The input to the tool.",
          "additionalProperties": true
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "ToolResultBlockParam": {
      "type": "object",
      "title": "Tool Result Block Parameter",
      "description": "A tool result content block providing the output from a tool invocation.",
      "required": ["type", "tool_use_id"],
      "properties": {
        "type": {
          "type": "string",
          "const": "tool_result"
        },
        "tool_use_id": {
          "type": "string",
          "description": "The id of the tool use request this is a result for."
        },
        "content": {
          "description": "The result of the tool call. Can be a string or array of content blocks.",
          "oneOf": [
            {
              "type": "string"
            },
            {
              "type": "array",
              "items": {
                "oneOf": [
                  { "$ref": "#/$defs/TextBlockParam" },
                  { "$ref": "#/$defs/ImageBlockParam" }
                ]
              }
            }
          ]
        },
        "is_error": {
          "type": "boolean",
          "description": "Set to true if the tool execution resulted in an error.",
          "default": false
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        }
      },
      "additionalProperties": false
    },
    "ThinkingBlock": {
      "type": "object",
      "title": "Thinking Block",
      "description": "A thinking content block showing Claude's internal reasoning process.",
      "required": ["type", "thinking", "signature"],
      "properties": {
        "type": {
          "type": "string",
          "const": "thinking"
        },
        "thinking": {
          "type": "string",
          "description": "Claude's internal reasoning text."
        },
        "signature": {
          "type": "string",
          "description": "A signature verifying the thinking block."
        }
      },
      "additionalProperties": false
    },
    "ThinkingBlockParam": {
      "type": "object",
      "title": "Thinking Block Parameter",
      "description": "A thinking content block in a request for multi-turn with extended thinking.",
      "required": ["type", "thinking", "signature"],
      "properties": {
        "type": {
          "type": "string",
          "const": "thinking"
        },
        "thinking": {
          "type": "string",
          "description": "The thinking text from a previous response."
        },
        "signature": {
          "type": "string",
          "description": "The signature from the previous thinking block."
        }
      },
      "additionalProperties": false
    },
    "ToolDefinition": {
      "type": "object",
      "title": "Tool Definition",
      "description": "Definition of a tool that the model can use.",
      "required": ["name", "input_schema"],
      "properties": {
        "name": {
          "type": "string",
          "description": "The name of the tool. Must match ^[a-zA-Z0-9_-]{1,64}$.",
          "pattern": "^[a-zA-Z0-9_-]{1,64}$",
          "examples": ["get_stock_price", "get_weather"]
        },
        "description": {
          "type": "string",
          "description": "A detailed description of what the tool does, when it should be used, and what each parameter means."
        },
        "input_schema": {
          "type": "object",
          "description": "JSON Schema object defining the expected parameters for the tool.",
          "required": ["type"],
          "properties": {
            "type": {
              "type": "string",
              "const": "object"
            },
            "properties": {
              "type": "object",
              "additionalProperties": true
            },
            "required": {
              "type": "array",
              "items": {
                "type": "string"
              }
            }
          }
        },
        "cache_control": {
          "$ref": "#/$defs/CacheControl"
        },
        "type": {
          "type": "string",
          "description": "The type of tool. Omit for custom tools. Use specific type identifiers for server tools."
        }
      }
    },
    "ToolChoice": {
      "type": "object",
      "title": "Tool Choice",
      "description": "How the model should use the provided tools.",
      "required": ["type"],
      "properties": {
        "type": {
          "type": "string",
          "description": "The tool choice strategy.",
          "enum": ["auto", "any", "tool", "none"]
        },
        "name": {
          "type": "string",
          "description": "The name of the specific tool to use. Required when type is 'tool'."
        },
        "disable_parallel_tool_use": {
          "type": "boolean",
          "description": "Whether to disable parallel tool use."
        }
      }
    },
    "ThinkingConfig": {
      "type": "object",
      "title": "Thinking Configuration",
      "description": "Configuration for extended thinking feature.",
      "required": ["type"],
      "properties": {
        "type": {
          "type": "string",
          "description": "Whether thinking is enabled, disabled, or adaptive.",
          "enum": ["enabled", "disabled", "adaptive"]
        },
        "budget_tokens": {
          "type": "integer",
          "description": "Maximum number of tokens for thinking. Minimum 1024 and must be less than max_tokens.",
          "minimum": 1024
        }
      }
    },
    "OutputConfig": {
      "type": "object",
      "title": "Output Configuration",
      "description": "Configuration for structured output format.",
      "properties": {
        "type": {
          "type": "string",
          "enum": ["json_schema"]
        },
        "schema": {
          "type": "object",
          "description": "JSON Schema defining the expected output structure.",
          "additionalProperties": true
        }
      }
    },
    "CacheControl": {
      "type": "object",
      "title": "Cache Control",
      "description": "Cache control settings for prompt caching. Creates cost-saving cache breakpoints for reusable context.",
      "required": ["type"],
      "properties": {
        "type": {
          "type": "string",
          "const": "ephemeral"
        },
        "ttl": {
          "type": "string",
          "description": "Time-to-live for the cache entry.",
          "enum": ["5m", "1h"]
        }
      },
      "additionalProperties": false
    },
    "Metadata": {
      "type": "object",
      "title": "Metadata",
      "description": "Request metadata for tracking and abuse prevention.",
      "properties": {
        "user_id": {
          "type": "string",
          "description": "An external identifier for the user making the request. Should be a UUID, hash, or other opaque identifier."
        }
      },
      "additionalProperties": false
    },
    "Usage": {
      "type": "object",
      "title": "Usage",
      "description": "Token usage information for the request.",
      "required": ["input_tokens", "output_tokens"],
      "properties": {
        "input_tokens": {
          "type": "integer",
          "description": "The number of input tokens consumed.",
          "examples": [25]
        },
        "output_tokens": {
          "type": "integer",
          "description": "The number of output tokens generated.",
          "examples": [150]
        },
        "cache_creation_input_tokens": {
          "type": "integer",
          "description": "The number of input tokens used to create a cache entry."
        },
        "cache_read_input_tokens": {
          "type": "integer",
          "description": "The number of input tokens read from cache."
        }
      },
      "additionalProperties": false
    },
    "TokenCount": {
      "type": "object",
      "title": "Token Count",
      "description": "Response from the count tokens endpoint.",
      "properties": {
        "input_tokens": {
          "type": "integer",
          "description": "The total number of input tokens in the message."
        }
      },
      "additionalProperties": false
    },
    "ModelInfo": {
      "type": "object",
      "title": "Model Info",
      "description": "Metadata about a Claude model.",
      "required": ["id", "type", "display_name", "created_at"],
      "properties": {
        "id": {
          "type": "string",
          "description": "Unique model identifier.",
          "examples": ["claude-sonnet-4-6", "claude-opus-4-6"]
        },
        "type": {
          "type": "string",
          "description": "Object type. Always 'model' for model objects.",
          "const": "model"
        },
        "display_name": {
          "type": "string",
          "description": "A human-readable name for the model.",
          "examples": ["Claude Sonnet 4.6", "Claude Opus 4.6"]
        },
        "created_at": {
          "type": "string",
          "format": "date-time",
          "description": "RFC 3339 datetime string representing when the model was released."
        }
      },
      "additionalProperties": false
    },
    "Error": {
      "type": "object",
      "title": "Error",
      "description": "An error response from the Anthropic API.",
      "required": ["type", "error"],
      "properties": {
        "type": {
          "type": "string",
          "const": "error"
        },
        "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."
            }
          }
        }
      },
      "additionalProperties": false
    }
  },
  "oneOf": [
    { "$ref": "#/$defs/CreateMessageRequest" },
    { "$ref": "#/$defs/Message" }
  ]
}