Support class methods for tool helpers

[marwq]

Currently the only way to provide a request-scope state for tools in the beta runner is a wrapper:

def setup_tools(user_id: int):
    @beta_tool(name='get_user')
    def get_user(id: int) -> str:
        if user_id != id:
            return 'Error: User doesn't have permission'
        return ...

    return [get_user]

# in router/interactor
user_id = 123
client.beta.tool_runner(
    ...,
    tools=setup_tools(user_id)
)

I suggest to add feature for passing context for tools:

@beta_tool(name='get_user')
def get_user(id: int, ctx: Context) -> str:
    if ctx['user_id'] != id:
        return 'Error: User doesn't have permission'
    return ...

client.beta.tool_runner(
    ...,
    tools=[get_user],
    context={'user_id': 1},
)

Or at least support for methods:

class FetchProduct
    def __init__(self, ctx: dict):
        self.ctx = ctx

    @beta_tool(name='fetch_product')
    def __call__(self, id: int) -> str:
        return self.ctx['session'].get(Product, id)

tools = [FetchProduct(ctx)]

Currently, it doesn't work because an error would be raised on the self argument.

[marwq]

Also I suggest considering of dishka or fastdepends dependency injection support for the tool runner and tools.

[fede-kamel]

I took a stab at this - the fix normalizes callable class instances by extracting their bound __call__ method before passing to pydantic's validate_call. This handles both the self parameter issue and the missing __name__ attribute.

Bound methods (like service.get_weather) also work since they're already proper method objects.

Here's the approach:

def _normalize_callable(func):
    if isfunction(func) or ismethod(func):
        return func
    if callable(func):
        call_method = func.__call__
        if ismethod(call_method):
            return call_method
    return func

Branch with the fix + tests: main...fix/callable-class-tools

Happy to open a PR if this looks like the right direction.