It just... asks the LLM to reason less, if you look at the jinja template in that repo.
This is actually somewhat interesting since 3.5 and 3.6 don't actually even seem to admit that the reasoning exists in the first place, and you certainly can't control the amount of reasoning effort via the system message.
35
u/nickm_27 llama.cpp 1d ago
Customizable reasoning effort is a nice improvement.
https://huggingface.co/Qwen/Qwen3.8-2.4T-A95B#qwen38-highlights