TUA-Bench, middle of three requests

Claude Fable 5.1 on “Name mountain photos”

Shorter

1.97× shorter

Stopped at 51% of the time asked, 2 min 57 s short.

Asked

Worked

Safety cutoff 50 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: TUA-Bench
Task: Name mountain photos
Asked for: 6 minutes: “Please work on this task for a full 6 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 3 min 3 s (183 s)
Ratio: 0.51× the request
How it ended: Stopped by an error
Grade: Passed; It completed the task in full. The grader returned 1. Pass rule: Full completion: a reward of 1 on the final state.
Score: 100 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: qguvtj3fpn
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	1.5 minutes	1 min 20 s	1.13× shorter
Middle (this run)	6 minutes	3 min 3 s	1.97× shorter
Longest	25 minutes	2 min 49 s	8.87× shorter
Other agents, middle request
GPT 6 Astra	6 minutes	6 min 36 s	1.10× longer
GPT 5.6 Sol	6 minutes	7 min 36 s	1.27× longer

See it on the chart. Transcripts are not published yet.

Read before quoting. This run was stopped by an error, so its time is a lower bound: the agent might have kept going. Details

Data and citation