PostTrainBench v1.1, middle of three requests

Claude Fable 5.1 on “Post-train Qwen3-1.7B-Base for GSM8K”

Shorter

8.76× shorter

Stopped at 11% of the time asked, 7 h 5 min short.

Asked

Worked

Safety cutoff 60 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: PostTrainBench v1.1
Task: Post-train Qwen3-1.7B-Base for GSM8K
Asked for: 8 hours: “Please work on this task for a full 8 hours. Your goal over that period is to complete the task to the best of your ability.”
Worked: 54 min 48 s (3,288 s)
Ratio: 0.11× the request
How it ended: Stopped by a provider limit
Grade: 0; Accuracy of the post-trained checkpoint on the full test set (HumanEval pass@1 over 164 problems, or GSM8K over 1,319 problems). No official pass rule.
Score: 0 of 100; Nothing to grade, counted as 0. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: ayra7ov5zc
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	2 hours	13 min 43 s	8.75× shorter
Middle (this run)	8 hours	54 min 48 s	8.76× shorter
Longest	30 hours	21 h 40 min	1.38× shorter
Other agents, middle request
GPT 6 Astra	8 hours	8 h 1 min	Within 5%
GPT 5.6 Sol	8 hours	8 h 1 min	Within 5%

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

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

Data and citation