[Feature]: Apply tool calling after reasoning steps in Reasoning models.

[LRriver]

🚀 The feature, motivation and pitch

QwQ-32B has just been open-sourced as a reasoning model that also supports tool calling. But right now, vLLM can't support tool calling and reasoning at the same time (#14429), nor can it support tool calling after reasoning.
If we could enable the reasoning model to perform tool calling after reasoning steps, it might lead to improved performance.

Alternatives

No response

Additional context

No response

Before submitting a new issue...

• Make sure you already searched for relevant issues, and asked the chatbot living at the bottom right corner of the documentation page, which can answer lots of frequently asked questions.

[WangErXiao]

I think this restriction can be removed, and currently DeepSeek does not support function calls. It would be quite straightforward to implement for QwQ-32B.

[WangErXiao]

I've finished a version. After testing, I'll submit a PR.

[jiangyinzuo]

This issue is duplicated with #14429

[LRriver]

This issue is duplicated with #14429

Thank you for your reminder. Indeed, there are some repetitions, but I mentioned two points in the feature. Besides making vllm able to use tool calling and reasoning at the same time (this part you mentioned has been covered in #14429, and I will add the citation), I also hope to support tool calling after the reasoning steps. I think these two points are distinct. For example, previously vllm could support both reasoning and structured output simultaneously, but it did not support structured output after the reasoning steps (#12619). This issue has just been fixed recently (#12955, #14114).

[LRriver]

I've finished a version. After testing, I'll submit a PR.

Thanks for your contribution! I'm so happy to see this issue resolved.