Humanity's Last Exam, longest of three requests
Claude Fable 5.1 on “Humanity's Last Exam item 21”
Shorter
17.83× shorterStopped at 6% of the time asked, 18 min 53 s short.
- Asked for
- 20 minutes
- Worked
- 1 min 7 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
- Benchmark
- Humanity's Last Exam
- Asked for
- 20 minutes: “Please work on this task for a full 20 minutes. Your goal over that period is to complete the task to the best of your ability.”
- Worked
- 1 min 7 s (67 s)
- Ratio
- 0.06× 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
- phgh77vnw4
- Data release
- 26 Sep 2026
Related runs
| Fable on this task | Asked | Worked | Split | Result |
|---|---|---|---|---|
| Shortest | 1.25 minutes | 1 min | 1.26× shorter | |
| Middle | 5 minutes | 1 min 1 s | 4.89× shorter | |
| Longest (this run) | 20 minutes | 1 min 7 s | 17.83× shorter | |
| Other agents, longest request | ||||
| GPT 6 Astra | 20 minutes | 20 min 12 s | Within 5% | |
| GPT 5.6 Sol | 20 minutes | 20 min 21 s | Within 5% | |
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Data and citation
Upstream: Phan et al., 2025