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portia.tool_decorator

Tool decorator for creating tools from functions.

tool​

def tool(fn: Callable[..., T]) -> type[Tool[T]]

Convert a function into a Tool class.

This decorator automatically creates a Tool subclass from a function by:

  • Using the function's docstring as the tool description
  • Creating an ID and name based on the function name
  • Generating input schema from function parameters and type hints
  • Determining output schema from return type annotation

Example:

@tool def add_numbers(a: int, b: int) -> int: """Add two numbers together.""" return a + b

Arguments:

  • fn - The function to convert to a Tool class

Returns:

A Tool subclass that wraps the original function

Raises:

  • ValueError - If the function has invalid signature or return type