Agents' Last Exam, longest of three requests

Claude Fable 5.1 on “Compress a 3D Gaussian Splatting scene without losing quality”

Shorter

1.28× shorter

Stopped at 78% of the time asked, 13 min 7 s short.

Asked

Worked

Safety cutoff 2 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Agents' Last Exam
Task: Compress a 3D Gaussian Splatting scene without losing quality
Asked for: 60 minutes: “Please work on this task for a full 60 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 46 min 53 s (2,813 s)
Ratio: 0.78× the request
How it ended: Ended on its own
Grade: Passed; It passed the task's checker in full. The grader returned 1. Pass rule: Full pass: a checker score of 1.
Score: 100 of 100; Graded afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: 4ap3uoat4q
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	4 minutes	43 min 45 s	10.94× longer
Middle	15 minutes	13 min 21 s	1.12× shorter
Longest (this run)	60 minutes	46 min 53 s	1.28× shorter
Other agents, longest request
GPT 6 Astra	60 minutes	1 h 2 min	Within 5%
GPT 5.6 Sol	60 minutes	1 h 1 min	Within 5%

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Data and citation