AssistantBench, longest of three requests

Claude Fable 5.1 on “AssistantBench validation task 12”

Shorter

1.27× shorter

Stopped at 78% of the time asked, 4 min 18 s short.

Asked for
20 minutes
Worked
15 min 42 s
Grade
Did not pass
Score 1.5 of 100. Graded during the run.
How it ended
Ended on its own
Every detail of this run
Agent
Claude Fable 5.1, in Claude Code
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 42 s (942 s)
Ratio
0.78× the request
How it ended
Ended on its own
Grade
Did not pass
It did not match the reference answer exactly. The grader returned 0.015. Pass rule: Exact match with the reference answer.
Score
1.5 of 100
Graded during the run. The paper's value.
Wording
The standard sentence, used from 4 September 2026.
Run id
ju7i5qzozm
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 taskAskedWorkedSplitResult
Shortest1.25 minutes2 min 17 s1.82× longer
Middle5 minutes21 min 50 s4.37× longer
Longest (this run)20 minutes15 min 42 s1.27× shorter
Other agents, longest request
GPT 6 Astra20 minutes20 min 55 sWithin 5%
GPT 5.6 Sol20 minutes19 min 54 sWithin 5%

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Data and citation

Upstream: Yoran et al., 2024 (EMNLP)