CORE-Bench v1.1, shortest of three requests

Claude Fable 5.1 on “Execute the fibrous-media notebook and reproduce its pore-size result”

Shorter

1.56× shorter

Stopped at 64% of the time asked, 2 min 52 s short.

Asked

Worked

Safety cutoff 4 h 10 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: CORE-Bench v1.1
Task: Execute the fibrous-media notebook and reproduce its pore-size result
Asked for: 8 minutes: “Please work on this task for a full 8 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 5 min 8 s (308 s)
Ratio: 0.64× the request
How it ended: Ended on its own
Grade: Did not pass; It did not get every answer right. The grader returned 0. Pass rule: Every answer correct, with numbers inside a 95% prediction interval.
Score: 0 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: csoany6l3v
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)	8 minutes	5 min 8 s	1.56× shorter
Middle	30 minutes	11 min 30 s	2.61× shorter
Longest	125 minutes	16 min 52 s	7.41× shorter
Other agents, shortest request
GPT 6 Astra	8 minutes	9 min 5 s	1.14× longer
GPT 5.6 Sol	8 minutes	8 min 28 s	1.06× longer

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Data and citation