OSWorld 2.0, middle of three requests

Claude Fable 5.1 on “FreeCAD bracket”

Shorter

1.41× shorter

Stopped at 71% of the time asked, 17 min 32 s short.

Asked

Worked

Safety cutoff 8 h 20 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: OSWorld 2.0
Task: FreeCAD bracket
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: 42 min 28 s (2,548 s)
Ratio: 0.71× the request
How it ended: Ended on its own
Grade: Did not pass; It did not meet every checkpoint. The grader returned 0.974. Pass rule: Binary completion: a score of 1.00, with every checkpoint met.
Score: 97.4 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: stm4dsegye
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	15 minutes	12 min 52 s	1.17× shorter
Middle (this run)	60 minutes	42 min 28 s	1.41× shorter
Longest	250 minutes	8 h 30 min	2.04× longer
Other agents, middle 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