OpenRouter · Schema

OpenRouter Chat Message

A single message exchanged in an OpenRouter chat completion request or response, compatible with the OpenAI chat completions schema.

Artificial IntelligenceGatewayLarge Language ModelsRouter

Properties

Name	Type	Description
role	string	The role of the message author.
content	object	Message content as a plain string or array of content parts.
name	string	Optional name of the message author.
tool_call_id	string	When role is tool, references the tool call this message responds to.
tool_calls	array

View JSON Schema on GitHub

JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/openrouter/refs/heads/main/json-schema/openrouter-chat-message-schema.json",
  "title": "OpenRouter Chat Message",
  "description": "A single message exchanged in an OpenRouter chat completion request or response, compatible with the OpenAI chat completions schema.",
  "type": "object",
  "required": ["role"],
  "properties": {
    "role": {
      "type": "string",
      "enum": ["system", "user", "assistant", "tool"],
      "description": "The role of the message author."
    },
    "content": {
      "oneOf": [
        { "type": "string" },
        {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "type": {
                "type": "string",
                "enum": ["text", "image_url"]
              },
              "text": { "type": "string" },
              "image_url": {
                "type": "object",
                "properties": {
                  "url": { "type": "string", "format": "uri" }
                }
              }
            },
            "required": ["type"]
          }
        }
      ],
      "description": "Message content as a plain string or array of content parts."
    },
    "name": {
      "type": "string",
      "description": "Optional name of the message author."
    },
    "tool_call_id": {
      "type": "string",
      "description": "When role is tool, references the tool call this message responds to."
    },
    "tool_calls": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "id": { "type": "string" },
          "type": { "type": "string", "enum": ["function"] },
          "function": {
            "type": "object",
            "properties": {
              "name": { "type": "string" },
              "arguments": { "type": "string" }
            },
            "required": ["name", "arguments"]
          }
        },
        "required": ["id", "type", "function"]
      }
    }
  }
}