Conciseness

The body is code-first with almost no prose ('Project Structure', 'API Design', 'Database Patterns' sections are pure executable examples), matching 'Efficient; minor instances of over-explanation'. It is not 5 because the anti-patterns list ('Callback hell - use async/await', 'Secrets in code - use environment variables') restates knowledge Claude already has, and the empty top-level section after the title wastes tokens.

Actionability

Every section contains complete, copy-paste-ready TypeScript covering route handlers with Zod validation, dependency injection at the composition root, domain errors with a global error handler, Kysely repositories and transactions, validated config, and unit/integration tests, matching 'Fully executable; copy-paste ready code... specific examples cover the common cases'.

Workflow Clarity

The body is a topical pattern catalog with clear sections but no sequenced process for applying the patterns together (e.g., add service function -> add repository method -> add route -> add test) and no validation checkpoints, matching 'Steps listed but validation gaps; sequence present but checkpoints missing or implicit'. It is not 4 because there is no explicit order of operations at all, only parallel examples.

Progressive Disclosure

No bundle files exist and the single-file body is organized into clear, navigable sections (Project Structure, API Design, Error Handling, Database Patterns, Configuration, Testing, Anti-Patterns) with no dangling references, matching 'Good structure; most content is appropriately placed'. It is not 5 because ~290 lines of full code examples (e.g., complete test files, transaction examples) are all inlined and could be split into reference files to keep SKILL.md a leaner overview.

Specificity

Names the domain ('Node.js backend patterns') plus concrete specifics ('Express/Fastify', 'repositories'), comparable to 'Names domain and 1-2 concrete actions'. It falls below anchor 4 because no actual actions or capabilities (e.g., 'build API routes', 'structure repositories') are stated, and above anchor 2 because it is more concrete than 'Processes PDF files'.

Completeness

A clear 'what' is present ('Node.js backend patterns with Express/Fastify, repositories') but 'when to use it' is entirely missing from the description, matching anchor 3 and capped there by the missing 'Use when...' guideline. It is not 4 since no trigger guidance exists even weakly in the description itself.

Trigger Term Quality

Includes natural terms users would say ('Node.js', 'backend', 'Express', 'Fastify', 'repositories'), matching 'Good keyword coverage; a few natural terms missing'. Not 5 because common phrasings like 'API', 'REST', 'routes', or 'server' are absent; not 3 because the framework names go beyond generic keywords.

Distinctiveness Conflict Risk

The Node.js-backend/Express/Fastify niche is mostly distinct with only minor overlap risk against sibling backend skills (e.g., a generic TypeScript or database skill), matching anchor 4. Not 5 because 'backend patterns' without explicit trigger phrases leaves some ambiguity versus other server-side skills.