Concise-9B reasons with 0.66x the tokens of Qwen3.5-9B at equal accuracy
Reasoning traces keep running after the answer has formed, so Concise-9B comes from two rounds of fine-tuning Qwen3.5-9B on its own shortest correct answers. On 8,983 held-out problems it uses 0.66x the tokens at a 32K thinking budget, with accuracy within 1 point. In the base model, 54-64% of thinking tokens come after the final answer is already fixed. The cost: with traces run to 80K tokens, Concise-9B solves 25 fewer of 1,276 hard problems.