The Driftproof receipt for writing-plans on Claude Fable 5, from Report 007, dated 2026-08-31, and what it can say.
writing-plans on claude-fable-5
Not measured
This receipt carries no verdict: it does not record that a model answered the run, and its run is marked incomplete.
Skill token cost: about +1758 input tokens per call, estimated from the SKILL.md length (not measured).
The two arms
| arm | mean | spread across cases | cases |
|---|---|---|---|
| with the skill | 0.847 | ± 0.034 | 7 |
| without the skill | 0.731 | ± 0.110 | 6 |
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-007/writing-plans-claude-fable-5-2026-08-31.json; run.transcripts records hashes-only.
Receipt hash: 5c48336fb87837ca9b5c835b811d06e6d9894008bd30d27d93b93c6248014412
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-007/writing-plans-claude-fable-5-2026-08-31.json
npx driftproof@0.28.0 validate writing-plans-claude-fable-5-2026-08-31.json