Terminal-Bench 4.0, middle of three requests

Claude Fable 5.1 on “Resolve a 20-claim heat-pump warranty exception queue”

Longer

1.59× longer

Worked 59% past the request, 8 min 51 s over.

Asked

Worked

Safety cutoff 2 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Terminal-Bench 4.0
Task: Resolve a 20-claim heat-pump warranty exception queue
Asked for: 15 minutes: “Please work on this task for a full 15 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 23 min 51 s (1,431 s)
Ratio: 1.59× the request
How it ended: Ending not labelled yet
Grade: Did not pass; It did not pass the task's tests. The grader returned 0. Pass rule: The task's tests pass.
Score: 0 of 100; Graded afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: ok2jlfvmk7
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	4 minutes	14 min 50 s	3.71× longer
Middle (this run)	15 minutes	23 min 51 s	1.59× longer
Longest	60 minutes	34 min 47 s	1.72× shorter
Other agents, middle request
GPT 6 Astra	15 minutes	15 min 30 s	Within 5%
GPT 5.6 Sol	15 minutes	15 min 37 s	Within 5%

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Data and citation