Optional argument support for smolagents

[murawakimitsuhiro]

Fixes This PR resolves the error in issue #10 (related huggingface/smolagents#626 )

Error output

k: {"type": v["type"], "description": v.get("description", "")}
KeyError: 'type'

The fix addresses cases where arguments are provided using the anyOf schema.

Changed

• Implemented support for handling functions with optional arguments when defined as Tools (primarily using FastMCP)
• Added tests for the modified functionality

Implementation approach for optional and default arguments

I've addressed three scenarios related to issue.

1. Optional arguments with None as default: text: str | None = None
2. Required arguments with default values: text: str = "hello"
3. Optional arguments without default values: text: str | None

The current implementation outputs the following forward function for each case

# case1
def forward(self, text=None) -> str:
   ...
   
# case2
def forward(self, text="hello") -> str:
   ...

# case3
def forward(self, text) -> str:
   ...

For optional arguments without default values (case 3), I chose to maintain the existing implementation approach, requiring CodeAgent to explicitly specify these values rather than automatically providing None. But I'm open to discussion on this design choice.

Thank you for reviewing this PR!

[grll]

@murawakimitsuhiro looks good to me at first glance I will pull it and test locally

[grll]

@murawakimitsuhiro just the lint complaining could you run ruff ?

[grll]

with regard to your comment:

For optional arguments without default values (case 3), I chose to maintain the existing implementation approach, requiring CodeAgent to explicitly specify these values rather than automatically providing None. But I'm open to discussion on this design choice.

case 3 in your example is not optional it's a regular positional argument isn't it? So in my view it makes sense to fail rather than defaulting to None.

In my view, case 3 is a positional argument which is not optional even though it might take None as a value so I agree.

[grll]

looks good to me I would just add case 3 to the tests as well and run ruff to pass the lint

[grll]

could we also add here the case 3? with text: str | None

[grll]

@murawakimitsuhiro all good, great work thanks a lot!

[murawakimitsuhiro]

@grll Thank you very much for the swift reply!

[kjozsa]

I just tested release 0.0.15 and it does solve my issue as well. Thank you to both!