Conciseness

The body is dense and operational — script template, jq walk() example, exact git commands — with no padding explaining generic concepts; the repo-specific data-flow note ("smudge side of the filter is always `cat`") is genuinely non-obvious. Minor trimmable repetition exists: the staging-safety rule appears in "Wiring it in" step 4, again in the verification checklist, and again in "Explicit prohibitions". This fits anchor 4 (efficient with minor over-explanation), not 5, and is well above anchor 3.

Actionability

Fully concrete guidance: a complete bash script template with header-comment format, an executable `walk(...)`/`with_entries(...)` jq program for nested keys, and exact verification commands (`git check-attr filter -- <path>`, `git hash-object --path=<path>`, `git rev-parse :'<path>'`). Placeholders like `<name>`/`<path>` are appropriate parameterization for a convention-template skill, matching the copy-paste-ready top anchor.

Workflow Clarity

A clear sequence — inspect convention, choose sentinel vs. deletion, implement script, wire in (numbered), verify — backed by an 8-item verification checklist and explicit feedback loops ("If a live runtime check shows a chosen sentinel is rejected... switch that one field to deletion... and re-verify"). The risky batch operation (renormalize/staging) is heavily validated, matching the top anchor with explicit checkpoints and error-recovery guidance.

Progressive Disclosure

A single self-contained SKILL.md with clear, well-ordered section headers and no bundle files; the only file references (`scripts/mask-codex-state.sh`, `justfile`) are to the target repo's convention, not bundle content. At ~158 lines it exceeds the under-50-lines simple-skill exception, and the long verification checklist is the one block that could plausibly live in a separate reference file — good structure with minor organization gaps, i.e. anchor 4 rather than 5.

Specificity

The description names a concrete domain through quoted operations like "scrub JSON values" and "add a Git clean filter", but never states what the skill itself does — the actions appear only as user-side trigger phrases. It exceeds anchor 2 (domain is specific, not generic) but falls short of anchor 4, which expects the skill's concrete actions to be listed as capabilities.

Completeness

The 'when' is fully explicit ("This skill should be used when the user asks to..."), and the 'what' is conveyed through the concrete trigger operations, but there is no direct capability statement (e.g. "Scrubs volatile values from committed config blobs using git clean filters"). Both are present as in anchor 4, though the 'what' relies on implication from the triggers rather than an explicit statement, keeping it below anchor 5.

Trigger Term Quality

Five natural, quotable trigger phrases — "scrub JSON values", "mask config fields", "add a Git clean filter", "remove volatile values from tracked config", "stop config churn" — cover synonym variations a user would genuinely say. This matches the anchor for comprehensive natural-term coverage.

Distinctiveness Conflict Risk

The niche — git clean filters for scrubbing tracked config values — is highly specific with distinct trigger phrases ("stop config churn", "add a Git clean filter") that are unlikely to fire for any other skill. This is a clear niche with minimal conflict risk, matching the top anchor.