tools-rs 0.3.3

Python decorator for defining tools-rs LLM tool functions

tools-rs

Python decorator for defining tools-rs LLM tool functions.

What is this?

tools-rs is a Rust framework for building, registering, and executing tools with automatic JSON schema generation for LLM integration. Its Python FFI adapter lets end users write tools in Python that get loaded into a Rust application.

This pip package provides the @tool decorator so your IDE can resolve imports, provide autocomplete, and type-check your tool definitions. At runtime, the Rust adapter auto-injects the same decorator — this package is optional and only needed for IDE support.

Usage

pip install tools-rs

Then write your tools:

from tools_rs import tool

@tool(requires_approval=False, cost_tier=1)
def weather(city: str, units: str = "celsius") -> str:
    """Get current weather for a city.

    Args:
        city: City name to look up
        units: Temperature unit (celsius or fahrenheit)
    """
    import requests
    resp = requests.get(f"https://wttr.in/{city}?format=j1")
    return resp.json()["current_condition"][0]["temp_C"]

The @tool decorator extracts:

• Name from the function name
• Description from the docstring (first paragraph)
• Parameter schema from type hints (str → "string", int → "integer", Literal["a", "b"] → enum, etc.)
• Parameter descriptions from Google-style Args: docstring blocks
• Required vs optional from default values
• Metadata from decorator keyword arguments

Supported type hints

Python type	JSON Schema
str	{"type": "string"}
int	{"type": "integer"}
float	{"type": "number"}
bool	{"type": "boolean"}
list[T]	{"type": "array", "items": ...}
Literal["a", "b"]	{"type": "string", "enum": ["a", "b"]}
Optional[T]	{"anyOf": [..., {"type": "null"}]}

License

MIT