Conciseness

The body is dense and directive — e.g. 'Add heartbeat ping/pong mechanism with configurable interval (default 30s) and timeout detection' — with no re-teaching of concepts Claude already knows. Minor trimmable padding remains: the Overview paragraph largely repeats the frontmatter description, and the Resources section (RFC 6455, socket.io docs links) adds little, keeping it at anchor 4 rather than the fully lean anchor 5.

Actionability

Guidance is concrete throughout: specific upgrade paths ('/ws', '/socket.io'), a defined message envelope ('type', 'channel', 'payload', 'correlationId'), concrete close codes (1008, 1006) with causes and fixes, and an explicit Output file layout. It is not anchor 5 because the body contains no executable code itself — it relies on references for runnable examples — and examples.md does provide them, so this is 'mostly executable guidance with minor gaps' rather than copy-paste ready in the body.

Workflow Clarity

The nine instructions form a coherent, correctly ordered sequence (examine framework → create server → authenticate → registry → protocol → rooms → heartbeat → Redis adapter → tests), and step 9 includes testing. It is not anchor 5 because there is no explicit validation checkpoint or feedback loop — the body never says to run the lifecycle tests, fix failures, and re-run — and it is above anchor 3 because a verification step (writing tests) is explicitly sequenced.

Progressive Disclosure

The body is a concise overview with three clearly signaled, one-level-deep references ([references/implementation.md], [references/errors.md], [references/examples.md]), all of which exist as real files. It falls short of anchor 5 because two of the referenced files do not deliver what the body promises: implementation.md contains generic REST-API design steps (OpenAPI/Swagger, CORS, HTTP endpoints) rather than the 'full implementation guide' for the WebSocket server described, and errors.md contains generic REST errors (429 rate limits, database connections) rather than 'comprehensive error patterns' for WebSocket.

Specificity

The description names the domain and a single concrete action — 'Build scalable WebSocket servers for real-time bidirectional communication' — with no further specific capabilities listed (no mention of connection lifecycle, rooms, heartbeat, or scaling specifics). It matches anchor 3 (domain plus 1-2 concrete actions, not comprehensive); it is not anchor 4 because it does not list several specific actions.

Completeness

Both parts are present: the 'what' ('Build scalable WebSocket servers for real-time bidirectional communication') and an explicit 'Use when...' clause plus concrete trigger phrases. It falls short of anchor 5 because the 'when' clause — 'Use when enabling real-time bidirectional communication' — circularly restates the 'what' rather than naming distinct usage scenarios; it is above anchor 4's midpoint because the trigger phrases add explicit, concrete invocation guidance.

Trigger Term Quality

Concrete natural trigger phrases are present: 'build WebSocket server', 'add real-time API', 'implement WebSocket'. Coverage is good but misses common variations users would say, such as 'Socket.IO', 'real-time messaging', or 'live updates', so it sits at anchor 4 rather than anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

'WebSocket server' is a clear niche with distinct triggers ('build WebSocket server', 'implement WebSocket'), giving minimal conflict risk with unrelated skills. It is not anchor 5 because the trigger 'add real-time API' is broad enough to overlap with closely related real-time/streaming/API skills.