TUA-Bench, middle of three requests

Claude Fable 5.1 on “Daily email report”

Shorter

2.53× shorter

Stopped at 40% of the time asked, 3 min 38 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: Daily email report
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: 2 min 22 s (142 s)
Ratio: 0.40× 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: kdvkdduiuk
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 11 s	1.26× shorter
Middle (this run)	6 minutes	2 min 22 s	2.53× shorter
Longest	25 minutes	2 min 9 s	11.67× shorter
Other agents, middle request
GPT 6 Astra	6 minutes	6 min 9 s	Within 5%
GPT 5.6 Sol	6 minutes	6 min 5 s	Within 5%
Muse Spark 1.3	6 minutes	2 min 14 s	2.69× shorter

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