How to build a function calling schema dict in Python

import json
from typing import Dict, Any, List, Optional


def build_function_schema(
    name: str,
    description: str,
    parameters: Optional[Dict[str, Any]] = None,
    required: Optional[List[str]] = None
) -> Dict[str, Any]:
    """Build an OpenAI-compatible function calling schema dictionary."""
    schema: Dict[str, Any] = {
        "type": "function",
        "function": {
            "name": name,
            "description": description,
            "parameters": {
                "type": "object",
                "properties": parameters or {},
                "required": required or []
            }
        }
    }
    return schema


if __name__ == "__main__":
    schema = build_function_schema(
        name="get_weather",
        description="Get the current weather for a city",
        parameters={
            "city": {"type": "string", "description": "City name"},
            "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]}
        },
        required=["city"]
    )
    print(json.dumps(schema, indent=2))