Claude · Schema

CreateMessageRequest

Artificial IntelligenceChatbotConversational AIGenerative AILarge Language ModelsMachine LearningNatural Language Processing

Properties

Name	Type	Description
model	string	The model that will complete your prompt. See the list of available models.
max_tokens	integer	The maximum number of tokens to generate before stopping. Different models support different maximum values.
messages	array	Input messages. Alternating user and assistant conversational turns. Maximum 100,000 messages per request.
system	object	System prompt providing context and instructions to Claude. Can be a string or array of content blocks.
temperature	number	Amount of randomness injected into the response. Ranges from 0.0 to 1.0. Use closer to 0.0 for analytical tasks, closer to 1.0 for creative tasks.
top_p	number	Use nucleus sampling. Recommended to use either temperature or top_p, but not both.
top_k	integer	Only sample from the top K options for each subsequent token.
stop_sequences	array	Custom text sequences that will cause the model to stop generating.
stream	boolean	Whether to incrementally stream the response using server-sent events.
metadata	object
tools	array	Definitions of tools that the model may use.
tool_choice	object
thinking	object
output_config	object
service_tier	string	Service tier to use for this request.
cache_control	object

View JSON Schema on GitHub

JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "#/components/schemas/CreateMessageRequest",
  "title": "CreateMessageRequest",
  "type": "object",
  "required": [
    "model",
    "max_tokens",
    "messages"
  ],
  "properties": {
    "model": {
      "type": "string",
      "description": "The model that will complete your prompt. See the list of available models.",
      "example": "claude-sonnet-4-6"
    },
    "max_tokens": {
      "type": "integer",
      "description": "The maximum number of tokens to generate before stopping. Different models support different maximum values.",
      "minimum": 1,
      "example": 1024
    },
    "messages": {
      "type": "array",
      "description": "Input messages. Alternating user and assistant conversational turns. Maximum 100,000 messages per request.",
      "items": {
        "$ref": "#/components/schemas/MessageParam"
      },
      "minItems": 1,
      "example": []
    },
    "system": {
      "description": "System prompt providing context and instructions to Claude. Can be a string or array of content blocks.",
      "oneOf": [
        {
          "type": "string"
        },
        {
          "type": "array",
          "items": {
            "$ref": "#/components/schemas/TextBlockParam"
          }
        }
      ],
      "example": "example_value"
    },
    "temperature": {
      "type": "number",
      "description": "Amount of randomness injected into the response. Ranges from 0.0 to 1.0. Use closer to 0.0 for analytical tasks, closer to 1.0 for creative tasks.",
      "minimum": 0.0,
      "maximum": 1.0,
      "default": 1.0,
      "example": 42.5
    },
    "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,
      "example": 42.5
    },
    "top_k": {
      "type": "integer",
      "description": "Only sample from the top K options for each subsequent token.",
      "minimum": 1,
      "example": 10
    },
    "stop_sequences": {
      "type": "array",
      "description": "Custom text sequences that will cause the model to stop generating.",
      "items": {
        "type": "string"
      },
      "example": []
    },
    "stream": {
      "type": "boolean",
      "description": "Whether to incrementally stream the response using server-sent events.",
      "default": false,
      "example": true
    },
    "metadata": {
      "$ref": "#/components/schemas/Metadata"
    },
    "tools": {
      "type": "array",
      "description": "Definitions of tools that the model may use.",
      "items": {
        "$ref": "#/components/schemas/Tool"
      },
      "example": []
    },
    "tool_choice": {
      "$ref": "#/components/schemas/ToolChoice"
    },
    "thinking": {
      "$ref": "#/components/schemas/ThinkingConfig"
    },
    "output_config": {
      "$ref": "#/components/schemas/OutputConfig"
    },
    "service_tier": {
      "type": "string",
      "description": "Service tier to use for this request.",
      "enum": [
        "auto",
        "standard_only"
      ],
      "default": "auto",
      "example": "auto"
    },
    "cache_control": {
      "$ref": "#/components/schemas/CacheControl"
    }
  }
}