Paper induces closed models to externalise reasoning through tool calls

single source· 1 articles · confidence: medium · first seen 2026-09-21 20:00 UTC

What this means for you

Nothing to build on today. The method is described in one preprint, so treat any claim about a named closed model's internal reasoning as that paper's finding, not a verified property. If it replicates, it is a way to observe reasoning that labs currently keep hidden.

A preprint reports that registering a custom tool through a standard API feature gets closed frontier models to write out the intermediate steps they normally keep hidden. Because such traces might be tidied-up explanations rather than the working itself, the authors first checked the method against models whose steps are already visible. They say the extracted traces match those results and beat no-reasoning baselines on competition maths, science and code generation. GPT-6 Astra, one closed model named, is described as finding a correct route earlier and writing out only the steps that matter. Single unreplicated source; no evaluation dates given.

Models in this story

Key facts

  • ·The study is posted as arXiv preprint 2609.26637, dated 21 September 2026. source
  • ·The authors induce models to externalise intermediate reasoning by registering a custom tool through a standard API feature. source
  • ·Extracted reasoning is reported to match native reasoning performance and substantially outperform no-reasoning baselines across competition mathematics, science and code generation. source
  • ·GPT-6 Astra is named among the closed-source frontier models tested. source
  • ·Astra is characterised as selecting a correct reasoning trajectory earlier, resolving elementary steps internally and externalising only crucial reasoning. source

What the sources say

Sources

The original reporting. Follow these — they did the work.

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