Humanity's Last Exam, middle of three requests

Claude Fable 5.1 on “Humanity's Last Exam item 17”

Shorter

1.77× shorter

Stopped at 57% of the time asked, 2 min 10 s short.

Asked for
5 minutes
Worked
2 min 50 s
Grade
Did not pass
Score 0 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
2 min 50 s (170 s)
Ratio
0.57× the request
How it ended
Ended on its own
Grade
Did not pass
It was not marked correct by the judge. The grader returned 0. Pass rule: The benchmark's own judge marks the answer correct.
Score
0 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
o3ixvrdbdu
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 17 s1.83× longer
Middle (this run)5 minutes2 min 50 s1.77× shorter
Longest20 minutes2 min 22 s8.46× shorter
Other agents, middle request
GPT 6 Astra5 minutes5 min 8 sWithin 5%
GPT 5.6 Sol5 minutes5 min 14 sWithin 5%

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Data and citation

Upstream: Phan et al., 2025