OSWorld 2.0, middle of three requests

Claude Fable 5.1 on “Radio bumper”

Shorter

1.18× shorter

Stopped at 85% of the time asked, 9 min 13 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: Radio bumper
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: 50 min 48 s (3,048 s)
Ratio: 0.85× the request
How it ended: Ended on its own
Grade: Did not pass; It did not meet every checkpoint. The grader returned 0.495. Pass rule: Binary completion: a score of 1.00, with every checkpoint met.
Score: 49.5 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: 2wc4jc556z
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	27 min 10 s	1.81× longer
Middle (this run)	60 minutes	50 min 48 s	1.18× shorter
Longest	250 minutes	4 h 12 min	Within 5%
Other agents, middle request
GPT 6 Astra	60 minutes	1 h 2 min	Within 5%
GPT 5.6 Sol	60 minutes	1 h 19 min	1.32× longer

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Data and citation