Sakana ALE-Bench, middle of three requests

Claude Fable 5.1 on “AtCoder Heuristic Contest 11”

Shorter

2.36× shorter

Stopped at 42% of the time asked, 28 min 50 s short.

Asked

Worked

Safety cutoff 6 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Sakana ALE-Bench
Task: AtCoder Heuristic Contest 11
Asked for: 50 minutes: “Please work on this task for a full 50 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 21 min 11 s (1,271 s)
Ratio: 0.42× the request
How it ended: Ending not labelled yet
Grade: 2,391,268,995; 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 2415; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: okvkjgf7uu
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	12.5 minutes	12 min 20 s	Within 5%
Middle (this run)	50 minutes	21 min 11 s	2.36× shorter
Longest	200 minutes	59 min 17 s	3.37× shorter
Other agents, middle request
GPT 6 Astra	50 minutes	50 min 21 s	Within 5%
GPT 5.6 Sol	50 minutes	50 min 27 s	Within 5%

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Data and citation