PaperBench, longest of three requests

Claude Fable 5.1 on “BAM”

Shorter

3.63× shorter

Stopped at 28% of the time asked, 58 min short.

Asked

Worked

Safety cutoff 2 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: PaperBench
Task: BAM
Asked for: 80 minutes: “Please work on this task for a full 80 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 22 min 1 s (1,321 s)
Ratio: 0.28× the request
How it ended: Ending not labelled yet
Grade: 0.671; Replication score: a weighted rubric of pass/fail leaf checks, 0 to 1, after a full reproduction attempt. No official pass rule.
Score: 67.1 of 100; Judged afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: 3mtjfhr4gu
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	5 minutes	6 min 14 s	1.25× longer
Middle	20 minutes	11 min 17 s	1.77× shorter
Longest (this run)	80 minutes	22 min 1 s	3.63× shorter
Other agents, longest request
GPT 6 Astra	80 minutes	1 h 21 min	Within 5%
GPT 5.6 Sol	80 minutes	1 h 31 min	1.14× longer

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Read before quoting. How this run ended has not been labelled yet. It is timed like every other run and counted in every number. Details

Data and citation