TUA-Bench, shortest of three requests

Claude Fable 5.1 on “Optimize cold plate”

Longer

2.96× longer

Worked 196% past the request, 11 min 47 s over.

Asked

Worked

Safety cutoff 3 h 20 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: TUA-Bench
Task: Optimize cold plate
Asked for: 6 minutes: “Please work on this task for a full 6 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 17 min 47 s (1,067 s)
Ratio: 2.96× the request
How it ended: Ended on its own
Grade: Did not pass; It did not complete the task in full. The grader returned 0.33. Pass rule: Full completion: a reward of 1 on the final state.
Score: 33 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: 4dszdxyjiy
Data release: 26 Sep 2026

The other requests for Claude Fable 5.1 on this task, and the other agents at this request
Fable on this task	Asked	Worked	Result
Shortest (this run)	6 minutes	17 min 47 s	2.96× longer
Middle	25 minutes	28 min 9 s	1.13× longer
Longest	100 minutes	35 min 45 s	2.80× shorter
Other agents, shortest request
GPT 6 Astra	6 minutes	6 min 30 s	1.08× longer
GPT 5.6 Sol	6 minutes	9 min 55 s	1.65× longer
Muse Spark 1.3	6 minutes	15 min 2 s	2.51× longer

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Data and citation