Terminal-Bench 4.0, middle of three requests

Claude Fable 5.1 on “Reconstruct a 3D corner tie from a 2D schematic”

Shorter

1.28× shorter

Stopped at 78% of the time asked, 4 min 22 s short.

Asked

Worked

Safety cutoff 2 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Terminal-Bench 4.0
Task: Reconstruct a 3D corner tie from a 2D schematic
Asked for: 20 minutes: “Please work on this task for a full 20 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 15 min 38 s (938 s)
Ratio: 0.78× the request
How it ended: Ended on its own
Grade: Passed; It passed the task's tests. The grader returned 1. Pass rule: The task's tests pass.
Score: 100 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: bayd5r7z6b
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	5 minutes	13 min 27 s	2.69× longer
Middle (this run)	20 minutes	15 min 38 s	1.28× shorter
Longest	80 minutes	20 min 25 s	3.92× shorter
Other agents, middle request
GPT 6 Astra	20 minutes	20 min 34 s	Within 5%
GPT 5.6 Sol	20 minutes	20 min 18 s	Within 5%

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