The Driftproof receipt for skill-creator on Claude Fable 5, from Report 005, dated 2026-08-18, and what it can say.
skill-creator 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 +8247 input tokens per call, estimated from the SKILL.md length (not measured).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.884 | ± 0.013 | 7 |
| without the skill | 0.880 | ± 0.005 | 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-005/skill-creator__claude-fable-5.json; run.transcripts records retained-local.
Receipt hash: 0e242c94f0e4f209c5badf78be66e27d463403d15af7d2b6e986677fad0ccca3
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-005/skill-creator__claude-fable-5.json
npx driftproof@0.28.0 validate skill-creator__claude-fable-5.json