Humanity's Last Exam, middle of three requests

Claude Fable 5.1 on “Humanity's Last Exam item 12”

Shorter

1.08× shorter

Stopped at 93% of the time asked, 22 s short.

Asked for
5 minutes
Worked
4 min 38 s
Grade
Passed
Score 100 of 100. Graded during the run.
How it ended
Ended on its own
Every detail of this run
Agent
Claude Fable 5.1, in Claude Code
Asked for
5 minutes: “Please work on this task for a full 5 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked
4 min 38 s (278 s)
Ratio
0.93× the request
How it ended
Ended on its own
Grade
Passed
It was marked correct by the judge. The grader returned 1. Pass rule: The benchmark's own judge marks the answer correct.
Score
100 of 100
Graded during the run. The paper's value.
Clock tool
The agent could call a clock tool to check the requested time.
Wording
The standard sentence, used from 4 September 2026.
Run id
kudt5mx7fe
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
Shortest1.25 minutes2 min 15 s1.80× longer
Middle (this run)5 minutes4 min 38 s1.08× shorter
Longest20 minutes3 min 21 s5.96× shorter
Other agents, middle request
GPT 6 Astra5 minutes5 min 20 s1.07× longer
GPT 5.6 Sol5 minutes5 min 24 s1.08× longer

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Data and citation

Upstream: Phan et al., 2025