OSWorld 2.0, middle of three requests

Claude Fable 5.1 on “Calc macros, contracts, and emails”

Shorter

1.11× shorter

Stopped at 90% of the time asked, 5 min 57 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: Calc macros, contracts, and emails
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: 54 min 3 s (3,243 s)
Ratio: 0.90× the request
How it ended: Ended on its own
Grade: Passed; It met every checkpoint. The grader returned 1.0. Pass rule: Binary completion: a score of 1.00, with every checkpoint met.
Score: 100 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: bxzcz6k7ge
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	26 min 58 s	1.80× longer
Middle (this run)	60 minutes	54 min 3 s	1.11× shorter
Longest	250 minutes	1 h 28 min	2.85× shorter
Other agents, middle request
GPT 6 Astra	60 minutes	1 h 3 min	Within 5%
GPT 5.6 Sol	60 minutes	1 h 41 min	1.68× longer

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Data and citation