[Bug] Tool calling kwargs

[ButterflyAtHeart]

What happened?

I am working with llama3.1 70 b and when calling tools in my react agent, the model sometimes predicts the next_tool_args to be {"foo": "bar"} instead of {"kwargs":{"foo":"bar"}.
This raises a ValueError: Arg foo is not in the tool's args.

I am not sure if this is a design choice, but if not please let me know, and I could try to implement a fix for this.

Steps to reproduce

import dspy
f = dspy.Tool(
            func=lambda **kwargs: "Completed.",
            name="finish",
            desc=f"Signals that the final outputs are now available and marks the task as complete.",
            args={}
        )
f(foo="bar")

DSPy version

2.6.10

[okhat]

Thank you @ButterflyAtHeart ! This makes sense; let's figure out how to fix it.

First, does this actually cause a problem? I guess it shows up in the trajectory as an exception, which is confusing to the user and to the model? Either way, yes we do want to fix this.

[ButterflyAtHeart]

You are right, it does not pose a real problem except showing up in trajectory, and maybe confusing the user as well as maybe saving another round of where the LLM has to correct this.
My current idea is to test for _ParameterKind.VAR_KEYWORD in the signature after line 88 of tools.py. and then setting a new instance variable of Tool, to look out for that. This we can then use to adjust Tool.__call__ .
If this sounds confusing I am sorry for that. I will open a PR tomorrow and you can check it out.

[okhat]

This makes sense but it sounds like it might add a bunch of code. I wonder how we can "fix" this by simply ignoring the args to finish entirely... I want to avoid making the code have a lot of special cases.