TUA-Bench, middle of three requests

Claude Fable 5.1 on “Fix MP3 metadata”

Shorter

1.69× shorter

Stopped at 59% of the time asked, 2 min 3 s short.

Asked

Worked

Safety cutoff 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: TUA-Bench
Task: Fix MP3 metadata
Asked for: 5 minutes: “Please work on this task for a full 5 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 2 min 57 s (177 s)
Ratio: 0.59× the request
How it ended: Stopped by an error
Grade: Passed; It completed the task in full. The grader returned 1. Pass rule: Full completion: a reward of 1 on the final state.
Score: 100 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: lm2g7dnqku
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	1.25 minutes	45 s	1.68× shorter
Middle (this run)	5 minutes	2 min 57 s	1.69× shorter
Longest	20 minutes	1 min 49 s	10.98× shorter
Other agents, middle request
GPT 6 Astra	5 minutes	5 min 24 s	1.08× longer
GPT 5.6 Sol	5 minutes	5 min 45 s	1.15× longer
Muse Spark 1.3	5 minutes	5 min 48 s	1.16× longer

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Read before quoting. This run was stopped by an error, so its time is a lower bound: the agent might have kept going. Details

Data and citation