Agents' Last Exam, longest of three requests

Claude Fable 5.1 on “Repair and calibrate an urban SUMO traffic simulation”

Shorter

2.37× shorter

Stopped at 42% of the time asked, 46 min 14 s short.

Asked

Worked

Safety cutoff 2 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Agents' Last Exam
Task: Repair and calibrate an urban SUMO traffic simulation
Asked for: 80 minutes: “Please work on this task for a full 80 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 33 min 46 s (2,026 s)
Ratio: 0.42× the request
How it ended: Ended on its own
Grade: Did not pass; It did not pass the task's checker in full. The grader returned 0. Pass rule: Full pass: a checker score of 1.
Score: 0 of 100; Graded afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: ese5couknj
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	5 minutes	1 h 55 min	23.05× longer
Middle	20 minutes	11 min 47 s	1.70× shorter
Longest (this run)	80 minutes	33 min 46 s	2.37× shorter
Other agents, longest request
GPT 6 Astra	80 minutes	1 h 20 min	Within 5%
GPT 5.6 Sol	80 minutes	1 h 21 min	Within 5%

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