Conciseness

The body is code-first with no explanation of concepts Claude already knows, but there is trimmable redundancy: the Endpoint wrapper boilerplate ('export const getUser = new Endpoint(fetchUser, { schema: User, name: ... })') repeats verbatim across the Firebase, Supabase, IndexedDB, and base examples, and the 'Function Name Mangling' section restates the name guidance already given as an inline comment ('Unique name (important if function names get mangled in production)'). Efficient with minor instances that could be trimmed — matches anchor 4, not 3, since nothing explains known concepts.

Actionability

Nearly all code is copy-paste-ready TypeScript with complete imports (base, Firebase, Supabase, WebSocket, mutations, extend), and the Detection section gives concrete scan targets ('Functions returning Promise<T>', 'SDK client methods'). Falls just short of anchor 5 due to minor gaps: the IndexedDB example calls openDB() without importing it (no 'idb' package import), and UserFilters is used undefined — 'mostly executable guidance; concrete code with minor gaps'.

Workflow Clarity

The sequence is clear and well-checkpointed at the skill-chain level: install → detect async functions → an explicit prerequisite ('Entity classes that must already exist. Apply the skill "data-client-schema" ... before writing endpoints') → wrap → use with hooks, plus 'Next Steps' pointing to data-client-react/vue. Not 5 because there is no explicit validation step for the wrapped endpoints (e.g., type-check or render the hook to confirm the schema normalizes); not 3 because the prerequisite and sequencing checkpoints are explicit, not implicit.

Progressive Disclosure

Verified against the actual bundle: references/Endpoint.md and references/Endpoint.vue.md both exist, the deep-linked anchor (references/Endpoint.md#members-not-args) is real in both files, and the Vue convention note ('read <name>.vue.md instead of <name>.md when it exists') matches the bundle layout. The body keeps only patterns inline and delegates the full API to one clearly signaled, one-level-deep reference — matches anchor 5 with no organization gaps.

Specificity

Names the domain ('@data-client/endpoint', 'Data Client hooks') and two concrete actions ('Set up @data-client/endpoint', 'Wraps existing async functions with Endpoint'), but stops there — no mention of mutations/side effects, cache configuration, or the SDK patterns the skill actually covers. Not the level above (4 requires 'several specific actions'), and clearly above level 2 since the actions are concrete rather than generic.

Completeness

Both parts are explicit: the 'what' ('Wraps existing async functions with Endpoint for use with Data Client hooks') and a 'when' clause ('Use after data-client-setup detects non-REST/GraphQL async patterns'). Not capped at 3 since an explicit trigger clause exists, but not 5 because the trigger is a skill-chain condition rather than concrete user-language trigger phrases (e.g., 'use when the user mentions Firebase, Supabase, or WebSockets').

Trigger Term Quality

Relevant domain keywords are present ('custom async operations', 'existing async functions', 'non-REST/GraphQL async patterns', 'Data Client hooks'), but the natural phrases a user would actually say — Firebase, Supabase, WebSocket, IndexedDB, third-party SDK — are absent. Fits the 'some relevant keywords but missing common variations or synonyms' anchor; not 4 because the missing terms are exactly the ones users would lead with.

Distinctiveness Conflict Risk

Clear niche with minimal conflict risk: it names the exact package, defines a distinct action (wrapping existing async functions), and explicitly boundaries itself against REST/GraphQL via the data-client-setup chaining condition. Cannot be 4 since there is no meaningful overlap with neighboring skills — the scope is precisely fenced.