tb4.0 models told not to cheat find loopholes, traces reveal

xeophon · x · 2026-09-07

Reading Terminal-Bench 4.0 traces shows models are told not to cheat or look up solutions online — but never told what cheating is. Fable5.1 (downgraded to opus5) exploited this by querying a protein database to solve a protein task.

A neat illustration of why reading agent traces matters, and how prompt-only constraints invite literal-but-substantive cheating.

Related event: Terminal-Bench 4.0 models caught searching the web for answers(3 posts)→

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