ProgramBench, middle of three requests

Claude Fable 5.1 on “kaushiksrini/parqeye”

Shorter

460.12× shorter

Stopped at 0% of the time asked, 2 h 5 min short.

Asked

Worked

Safety cutoff 16 h 40 min, off the scale

Asked for: 125 minutes
Worked: 16 s
Grade: No grade recorded; This run is outside the paper's scores, and the campaign recorded no grade for it. Not in the paper's scores.
How it ended: Refused within 30 seconds

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: ProgramBench
Task: kaushiksrini/parqeye
Asked for: 125 minutes: “Please work on this task for a full 125 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 16 s (16 s)
Ratio: 0.00× the request
How it ended: Refused within 30 seconds
Grade: No grade recorded; This run is outside the paper's scores, and the campaign recorded no grade for it.
Wording: The standard sentence, used from 4 September 2026.
Run id: asciqpvj63
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	30 minutes	16 min 17 s	1.84× shorter
Middle (this run)	125 minutes	16 s	460.12× shorter
Longest	500 minutes	32 min 36 s	15.34× shorter
Other agents, middle request
GPT 6 Astra	125 minutes	2 h 6 min	Within 5%
GPT 5.6 Sol	125 minutes	2 h 5 min	Within 5%

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Data and citation