ProgramBench, shortest of three requests

Claude Fable 5.1 on “kaushiksrini/parqeye”

Shorter

1.84× shorter

Stopped at 54% of the time asked, 13 min 43 s short.

Asked

Worked

Safety cutoff 16 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: ProgramBench
Task: kaushiksrini/parqeye
Asked for: 30 minutes: “Please work on this task for a full 30 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 16 min 17 s (977 s)
Ratio: 0.54× the request
How it ended: Stopped by an error
Grade: Did not pass; It did not pass every hidden test. The grader returned 0.653. Pass rule: Resolved: every hidden test passes.
Score: 65.3 of 100; Graded afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: sfy3twpdcv
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)	30 minutes	16 min 17 s	1.84× shorter
Middle	125 minutes	16 s	460.12× shorter
Longest	500 minutes	32 min 36 s	15.34× shorter
Other agents, shortest request
GPT 6 Astra	30 minutes	30 min 54 s	Within 5%
GPT 5.6 Sol	30 minutes	16 h 40 min	33.33× longer

See it on the chart. Transcripts are not published yet.

Read before quoting. This run was stopped by an error, so its time is a lower bound: the agent might have kept going. Details

Data and citation