The Driftproof receipt for writing-clearly-and-concisely on Claude Fable 5, from Report 004, dated 2026-08-16, and what it can say.
writing-clearly-and-concisely on claude-fable-5
Not measured
This receipt carries no verdict: it does not record that a model answered the run.
Skill token cost: about +941 input tokens per call, estimated from the SKILL.md length (not measured).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.870 | ± 0.024 | 7 |
| without the skill | 0.858 | ± 0.037 | 7 |
No lift is stated for a state that did not measure one. A spread is the sample standard deviation of the per-case means: a descriptive spread with no coverage probability. The verdict above reads each case's two bands, not these aggregates.
What was verified
receipt_hash verified when this page was built from receipts/report-004/writing-clearly-and-concisely__claude-fable-5.json; run.transcripts records retained-local.
Receipt hash: ee8a9ce195ba40d3def6174eb32c42bf8279cb92ec7f1ca5f17a5679e8000622
Check this file yourself
validate shows that this file is unchanged since it was sealed. It does not show who made it or who sealed it.
curl -fsSLO https://raw.githubusercontent.com/driftproofhq/driftproof/main/receipts/report-004/writing-clearly-and-concisely__claude-fable-5.json
npx driftproof@0.28.0 validate writing-clearly-and-concisely__claude-fable-5.json