Conciseness

The body is lean: dense, working code examples with almost no conceptual padding, and no explanations of what JUnit/Mockito are. A few minor instances could be trimmed — 'Patterns: Arrange-Act-Assert' and the closing 'Keep tests fast, isolated, and deterministic' restate knowledge Claude already has — matching 'Efficient; minor instances of over-explanation that could be trimmed' rather than the every-token-earns-its-place level of a 5.

Actionability

Mostly executable guidance: complete test classes for each layer, a copy-paste JaCoCo plugin snippet, and concrete CI commands ('mvn -T 4 test', './gradlew test jacocoTestReport'). Minor gaps keep it below 5 — the persistence example references an undefined 'TestContainersConfig.class', and the Testcontainers section mentions '@DynamicPropertySource' wiring without showing it — fitting 'Mostly executable guidance; concrete code or commands with minor gaps'.

Workflow Clarity

The TDD sequence (write failing tests → implement → refactor → enforce coverage) is clearly listed, but validation checkpoints are only implicit — 'they should fail' hints at red-state verification, yet no step tells Claude to run a specific command (e.g. 'mvn test') to confirm failure or greenness before proceeding. This matches 'Steps listed but validation gaps; sequence present but checkpoints missing or implicit'.

Progressive Disclosure

The body is well-organized into clear per-layer sections (unit, web, integration, persistence, coverage, CI) with no bundle files and no nested references, so inlining is appropriate. Some content — the full JaCoCo pom snippet and four complete test classes — could live in reference files to slim the main skill, but as a self-contained skill under ~160 lines the structure fits 'Good structure; most content appropriately placed; minor organization gaps'.

Specificity

The description names the domain ("Test-driven development for Spring Boot") and a tool stack ("JUnit 5, Mockito, MockMvc, Testcontainers, and JaCoCo"), but describes only one action — test-driven development itself — without concrete capabilities like writing unit/integration tests or enforcing coverage. This matches the anchor 'Names domain and 1-2 concrete actions, but not comprehensive'; a 4 would require several specific listed actions.

Completeness

Both parts are present: what ("Test-driven development for Spring Boot using JUnit 5, Mockito, MockMvc, Testcontainers, and JaCoCo") and when ("Use when adding features, fixing bugs, or refactoring"). The 'when' clause is explicit but generic — it lacks concrete trigger phrases tied to testing (e.g. mentions of tests, coverage, or Spring Boot work), matching 'Has both what and when; when could be more explicit or specific'.

Trigger Term Quality

Triggers like "adding features, fixing bugs, or refactoring" are natural phrases users say, backed by searchable keywords ("Spring Boot", "Test-driven development", tool names). Common variations users would actually say — e.g. "writing tests", "test coverage", "unit tests" — are missing, matching 'Good keyword coverage; a few natural terms missing' rather than the comprehensive synonym coverage of a 5.

Distinctiveness Conflict Risk

The niche is clear — Spring Boot TDD with a named toolchain — distinguishing it from general testing or PDF/document skills. However, the trigger list ("adding features, fixing bugs, or refactoring") applies to almost any development task on a Spring Boot project, creating minor overlap with general refactoring/coding skills; this fits 'Mostly distinct; minor overlap risk with closely related skills'.