{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$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"]
      }
    }
  }
}