Users report that adding tools to Qwen 3.5 eliminates overthinking issues and produces more concise, natural responses.

Qwen 3.5 exhibits overthinking behavior when no tools are available, using a verbose Gemini 3/Gemma 4-style reasoning format

Enabling tools for Qwen 3.5 switches the model to a shorter, more natural Claude-like reasoning style that reduces overthinking

Setting the presence_penalty parameter to 1.0-1.5 is recommended as a first step to address the overthinking problem

This solution has remained relevant two months after Qwen 3.5's release, with users still reporting the overthinking issue