{
  "type": "object",
  "properties": {
    "id": {
      "type": "string",
      "description": "Unique identifier for the chat session."
    },
    "object": {
      "type": "string",
      "enum": ["chat.completion"],
      "description": "Type of object returned. In this case, 'chat.completion'."
    },
    "created": {
      "type": "integer",
      "description": "UNIX timestamp (seconds since epoch) when the response was created."
    },
    "choices": {
      "type": "array",
      "description": "Array of completion choices.",
      "items": {
        "type": "object",
        "properties": {
          "index": {
            "type": "integer",
            "description": "Index of the completion choice in the response array."
          },
          "message": {
            "type": "object",
            "properties": {
              "role": {
                "type": "string",
                "enum": ["system", "user", "assistant", "function"],
                "description": "The role of the entity producing this message."
              },
              "content": {
                "type": ["string", "null"],
                "description": "The content of the message, or null if not applicable."
              },
              "name": {
                "type": ["string", "null"],
                "pattern": "^[a-zA-Z0-9_-]{1,64}$",
                "description": "Optional name for the function or user associated with this message, matching the pattern a-z, A-Z, 0-9, underscores, or dashes."
              },
              "tool_calls": {
                "type": ["array", "null"],
                "description": "Tool calls made by the assistant, or null if none.",
                "items": {
                  "type": "object",
                  "properties": {
                    "tool_name": {
                      "type": "string",
                      "description": "Name of the tool called."
                    },
                    "parameters": {
                      "type": "object",
                      "description": "Parameters passed to the tool."
                    }
                  },
                  "required": ["tool_name", "parameters"]
                }
              },
              "image_url": {
                "type": ["string", "null"],
                "format": "uri",
                "description": "URL of the image contained in the message, or null if not present."
              }
            },
            "required": ["role"]
          },
          "finish_reason": {
            "type": ["string", "null"],
            "enum": ["stop", "length", "function_call", null],
            "description": "Reason why the completion process ended (e.g., length, function call, or stop)."
          }
        },
        "required": ["index", "message"]
      }
    },
    "usage": {
      "type": "object",
      "description": "Details about token usage in the request.",
      "properties": {
        "prompt_tokens": {
          "type": "integer",
          "description": "Number of tokens used in the prompt."
        },
        "completion_tokens": {
          "type": "integer",
          "description": "Number of tokens used in the completion."
        },
        "total_tokens": {
          "type": "integer",
          "description": "Total number of tokens used (prompt + completion)."
        }
      },
      "required": ["prompt_tokens", "completion_tokens", "total_tokens"]
    }
  },
  "required": ["id", "object", "created", "choices", "usage"],
  "additionalProperties": false
}