Conciseness

The ~45-line body is lean and assumes Claude's competence: it never explains what Flyway or a migration is, and every sentence is imperative project-specific direction ('Write only the tables, columns, and constraints the use case needs', 'Never touches an applied migration'). Nothing can be trimmed without losing information, matching the 5 rather than the 4 anchor.

Actionability

Concrete, executable guidance is present — the naming convention 'V<n>__<description>.sql', exact marker syntax '-- UC-XXX BR-YYY: <rule> on the line above it', and a copy-paste Handover template — but no example SQL of a migration showing the naming and marker conventions in situ. For an instruction-only skill this is the 'concrete guidance with minor gaps' of the 4 anchor; it falls short of 5 because the core artifact (a V-file) is never exemplified.

Workflow Clarity

The four steps are clearly sequenced with a conditional branch ('When the schema already has everything, write nothing and say so in the Handover'), but there is no validation or verification step — nothing confirms the chosen version number is free after writing, that each constraint traces to the entity model, or that the SQL is sound. Per the rubric's scoring notes, database operations without a validate-feedback loop cap workflow_clarity at 3, which matches the 'steps listed but validation gaps' anchor.

Progressive Disclosure

The under-50-line body is cleanly sectioned, and the verbatim Markers rows are appropriately split into a real, clearly signaled one-level-deep reference ([references/markers.md](references/markers.md)) rather than inlined. The unreferenced references/layer.md is self-documented infrastructure for /stack's glob discovery, not skill content, so it does not constitute a navigation gap — the content matches the 5 anchor.

Specificity

The description lists multiple concrete actions — 'versioned V*.sql scripts with sequences, tables, snake_case columns, CHECK and UNIQUE constraints, and foreign keys from the entity model' and 'Marks a constraint that enforces a business rule with -- UC-XXX BR-YYY' — with comprehensive, non-abstract coverage in third person. It is not the 4 anchor because there are no minor coverage gaps; every clause names a concrete capability.

Completeness

It explicitly answers both 'what' ('Builds the migration layer of a use case (UC-XXX) with Flyway: ...') and 'when' ('Use when the user asks to ... or mentions Flyway, schema migration, ...') with concrete trigger phrases, and adds boundary guidance ('Test data migrations belong to the test skills'). This is the 5 anchor verbatim in structure; the 4 anchor's 'when could be more explicit' does not apply since the when-clause enumerates exact utterances.

Trigger Term Quality

It covers natural user phrasings ('create a migration', 'write a Flyway migration', 'add a column', 'create the tables for UC-001', 'set up the database schema') plus synonyms ('schema migration, DB migration, database versioning, or SQL migration files') and the file-extension form ('V*.sql'). This matches the 5 anchor's comprehensive synonym/extension coverage; the 4 anchor would require missing natural terms, and none are missing.

Distinctiveness Conflict Risk

The skill occupies a clear niche — Flyway schema migrations driven by a use case entity model — with distinct triggers (Flyway, V*.sql, SQL migration files) and explicit de-scoping of test data. The 4 anchor's 'minor overlap risk with closely related skills' is not present: the trigger set is scoped to 'a project that combines layer plugins' and test-migration territory is explicitly excluded.