Conciseness

The ~30-line body is lean and dense with no padding, no explanation of concepts Claude already knows, and no filler; every line carries a directive ('Compare keeping, deleting, merging, inlining and replacing', 'rank concrete findings P0 through P3'). It clearly matches anchor 5 ('lean and efficient; assumes Claude's competence; every token earns its place') and shows none of the over-explanation that would drop it to anchor 4.

Actionability

There is some concrete guidance — 'Search the old names and their word variants with `git grep --untracked`' and 'rank concrete findings P0 through P3' — but most directives are abstract decision rules ('Classify every noun by its honest package, registry or application owner', 'a matched pre-acceptance probe') with no example of an ideal call site, a ranked finding, or what the probe is. This fits anchor 3 ('some concrete guidance but incomplete; missing key details'), below anchor 4's 'mostly executable guidance'.

Workflow Clarity

A rough sequence exists for each mode (read → inspect → show → classify → compare for design; rank → recommend for review; update contract → search old names → regenerate → forward-test for repair), but steps are never enumerated and checkpoints are implicit rather than explicit; only 'forward-test the real call' reads as verification. This matches anchor 3 ('steps listed but validation gaps; checkpoints missing or implicit') and does not reach anchor 4's 'clear sequence with most checkpoints present'.

Progressive Disclosure

No bundle files exist, so everything lives in a single body that is under 50 lines, but organization is a wall of flowing prose under one '# Best API' heading with no sections for the design/review/repair modes. External artifacts ('VISION.md', '`benchmark`', 'the Plan playbook', 'verdict') are referenced without being clearly signaled or linked. This fits anchor 3 ('some structure but could be better organized; references present but not clearly signaled'), below the well-organized-sections bar of the simple-skill exception.

Specificity

The description names its domain ('a Plate public call shape') and three actions ('Design, review or repair'), but phrases like 'live Slate-based contracts, ideal call sites, inference and ownership' are jargon-dense rather than concrete capabilities. It matches anchor 3: domain plus a couple of concrete actions, not comprehensive; it is below anchor 4 because the supporting terms add abstraction rather than specific, scannable capabilities.

Completeness

The 'what' is clear (design, review, or repair a Plate public call shape), but there is no 'Use when...' clause or equivalent explicit trigger guidance anywhere, which caps completeness at 3 per the judging guidelines. It fits anchor 3 ('clear what but when is missing or only weakly implied') and cannot reach anchor 4, which requires both what and when.

Trigger Term Quality

Relevant keywords exist ('Plate', 'Slate', 'call shape', 'review', 'repair') but common natural variations users would say — 'API', 'public API', 'interface', 'breaking change' — are missing, and 'call shape' is not a phrase a user would naturally utter. This sits at anchor 3 ('some relevant keywords but missing common variations or synonyms'), below anchor 4's 'good keyword coverage'.

Distinctiveness Conflict Risk

Naming the specific stack ('Plate', 'Slate') gives it a clear niche with low risk of triggering for unrelated skills, fitting mostly-anchor-4 ('mostly distinct; minor overlap risk'). It falls short of anchor 5 because without explicit trigger phrases it could still overlap with generic code-review or API-design skills in the same repo, and distinctness rests on framework names rather than distinct triggers.