handle empty tool call function arguments

[jimkring]

This pull request includes changes to improve the handling of tool calls in the mirascope/core package. The updates ensure that the model_json is properly initialized even when tool_call.function.arguments is empty.

Background:
LLMs sometimes use pass an empty string for tool call function args, which was causing an unhandled exception when deserializing the function arguments string to json with jiter.

Solution:
Now, we detect that tool_call.function.arguments is empty and simply initialize an empty dictionary (instead of trying to deserialize an empty string).

Changes to tool call handling:

• mirascope/core/azure/tool.py: Added a check to initialize model_json to an empty dictionary if tool_call.function.arguments is empty in the from_tool_call method.
• mirascope/core/groq/tool.py: Added a check to initialize model_json to an empty dictionary if tool_call.function.arguments is empty in the from_tool_call method.
• mirascope/core/openai/tool.py: Added a check to initialize model_json to an empty dictionary if tool_call.function.arguments is empty in the from_tool_call method.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (64c7ea5) to head (72b2d95).
Report is 6 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files          398       398           
  Lines        13298     13292    -6     
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- Hits         13298     13292    -6     

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[willbakst]

@jimkring good catch!

could you also update the remaining 7 providers?

[jimkring]

@willbakst I'll take a look. I did a search and only found those three identical bits of code. Maybe the other providers are subtly different.

[willbakst]

@willbakst I'll take a look. I did a search and only found those three identical bits of code. Maybe the other providers are subtly different.

oh you're right because of the issue being with jiter

can you update mistral to match the new recommended style from my other comment?

also, i just noticed that gemini and vertex have an issue where it will not allow empty args (when it should), would be great if you could update those as well as part of this

[jimkring]

@willbakst I've updated several other files/providers. Please take a look at how the differ in subtle ways. In some cases the arguments from the tool call are coming from the provide as a string, in other cases it's a Pydantic model. I don't have a way to test all these special cases, so we'll want to be thoughtful about our review and scope of changes.

[willbakst]

so we'll want to be thoughtful about our review and scope of changes.

happy to provide comments, also happy to take this over the finish line, just let me know :)

[jimkring]

@willbakst it's all yours to finish up, now. Thanks for the style suggestions and fixes -- I learned a couple things 👍

[willbakst]

this is now released in v1.10.1

thank you for the contribution!!