ProgramBench, shortest of three requests

Claude Fable 5.1 on “lfos/calcurse”

Shorter

2.88× shorter

Stopped at 35% of the time asked, 16 min 19 s short.

Asked for
25 minutes
Worked
8 min 41 s
Grade
Did not pass
Score 51.5 of 100. Graded afterwards.
How it ended
Ended on its own
Every detail of this run
Agent
Claude Fable 5.1, in Claude Code
Benchmark
ProgramBench
Asked for
25 minutes: “Please work on this task for a full 25 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked
8 min 41 s (521 s)
Ratio
0.35× the request
How it ended
Ended on its own
Grade
Did not pass
It did not pass every hidden test. The grader returned 0.515. Pass rule: Resolved: every hidden test passes.
Score
51.5 of 100
Graded afterwards. The paper's value.
Wording
The standard sentence, used from 4 September 2026.
Run id
73gv26uk6w
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 taskAskedWorkedSplitResult
Shortest (this run)25 minutes8 min 41 s2.88× shorter
Middle100 minutes2 h 16 min1.36× longer
Longest400 minutes5 h 23 min1.24× shorter
Other agents, shortest request
GPT 6 Astra25 minutes25 min 14 sWithin 5%
GPT 5.6 Sol25 minutes23 min 42 s1.05× shorter

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Data and citation

Upstream: Yang et al., 2026