Sakana ALE-Bench, middle of three requests

Claude Fable 5.1 on “AtCoder Heuristic Contest 26”

Shorter

1.41× shorter

Stopped at 71% of the time asked, 11 min 35 s short.

Asked

Worked

Safety cutoff 5 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Sakana ALE-Bench
Task: AtCoder Heuristic Contest 26
Asked for: 40 minutes: “Please work on this task for a full 40 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 28 min 25 s (1,705 s)
Ratio: 0.71× the request
How it ended: Ending not labelled yet
Grade: 1,414,820; Raw score on the private test cases, in each problem's own units; also reports rank against human contest entrants. No official pass rule.
Score: Performance 2940; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: jjvcamanxy
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	10 minutes	7 min 46 s	1.29× shorter
Middle (this run)	40 minutes	28 min 25 s	1.41× shorter
Longest	150 minutes	1 h 13 min	2.07× shorter
Other agents, middle request
GPT 6 Astra	40 minutes	40 min 35 s	Within 5%
GPT 5.6 Sol	40 minutes	40 min 56 s	Within 5%

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Data and citation