PaperBench, middle of three requests

Claude Fable 5.1 on “BAM”

Shorter

1.77× shorter

Stopped at 56% of the time asked, 8 min 43 s 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: 20 minutes: “Please work on this task for a full 20 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 11 min 17 s (677 s)
Ratio: 0.56× the request
How it ended: Ending not labelled yet
Grade: 0.535; Replication score: a weighted rubric of pass/fail leaf checks, 0 to 1, after a full reproduction attempt. No official pass rule.
Score: 53.5 of 100; Judged afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: ppx3s34glv
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 (this run)	20 minutes	11 min 17 s	1.77× shorter
Longest	80 minutes	22 min 1 s	3.63× shorter
Other agents, middle request
GPT 6 Astra	20 minutes	20 min 10 s	Within 5%
GPT 5.6 Sol	20 minutes	24 min 7 s	1.21× longer

See it on the chart. Transcripts are not published yet.

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