Sakana ALE-Bench, shortest of three requests

Claude Fable 5.1 on “AtCoder Heuristic Contest 26”

Shorter

1.29× shorter

Stopped at 78% of the time asked, 2 min 14 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: 10 minutes: “Please work on this task for a full 10 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 7 min 46 s (466 s)
Ratio: 0.78× the request
How it ended: Ending not labelled yet
Grade: 1,371,081; 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 1460; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: surnpnhrn6
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)	10 minutes	7 min 46 s	1.29× shorter
Middle	40 minutes	28 min 25 s	1.41× shorter
Longest	150 minutes	1 h 13 min	2.07× shorter
Other agents, shortest request
GPT 6 Astra	10 minutes	10 min 13 s	Within 5%
GPT 5.6 Sol	10 minutes	15 min 18 s	1.53× longer

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Data and citation