Conciseness

The ~25-line body is lean and assumes Claude's competence: no explanations of what webhooks are, no padding, every sentence carries operational content ('Capture raw body', 'Make handlers idempotent because Zoom can retry delivery'). Matches the score-5 anchor 'lean and efficient; every token earns its place'.

Actionability

Steps are directionally concrete ('Implement endpoint verification and signature verification before processing business logic', 'Separate webhook ingestion from downstream API calls with a queue') but contain no executable code, commands, or specific API details — the actual how-to lives entirely in reference files. This fits the score-3 anchor 'Some concrete guidance but incomplete... missing key details'; short of score 4 which expects concrete code or commands with only minor gaps.

Workflow Clarity

The six steps form a clear, correctly-ordered sequence (identify scope → verify before processing → store metadata → idempotency → queueing → debug checklist), with a verification checkpoint in step 2 and an explicit error-recovery path in step 6 ('checking endpoint reachability, TLS, validation token handling, signature base string...'). Matches score 4 ('clear sequence with most checkpoints present; minor validation gaps'), below score 5 which requires an explicit validate-fix-retry feedback loop.

Progressive Disclosure

The overview-to-references structure is present and clearly signaled, but navigation is undermined by three concrete defects: the listed 'troubleshooting/common-issues.md' does not exist in the bundle (broken link), 'references/signature-verification.md' is a 5-line stub that redirects to verification.md (a two-level reference chain the rubric penalizes), and two real bundle files (verification.md, environment-variables.md) are not directly reachable from SKILL.md. Fits score 3 ('some structure but could be better organized; references present but not clearly signaled') rather than score 4's 'references mostly clear'.

Specificity

The description names a concrete domain ('building Zoom webhooks') but contains zero capability actions — nothing about what the skill actually does (endpoint verification, subscription creation, signature validation, idempotent handling). This matches the score-2 anchor 'Names the domain but actions are minimal or generic' ('Processes PDF files'), and is above score 1 only because 'Zoom webhooks' is a concrete domain rather than pure abstraction.

Completeness

Only the 'when' is present ('Use when building Zoom webhooks') with no 'what' — the description never states what the skill does. This is a direct match for the score-2 anchor 'only "when" is present without "what"' (example: 'Use when working with documents'), and clearly below score 4 ('has both what and when').

Trigger Term Quality

It contains the core natural phrases 'Zoom' and 'webhooks' that a user would say, but offers no variations or synonyms ('Zoom events', 'event subscriptions', 'webhook endpoint', 'event delivery'). This fits the score-3 anchor 'Some relevant keywords but missing common variations or synonyms' ('Works with PDF files'), short of score 4's 'good keyword coverage'.

Distinctiveness Conflict Risk

'Zoom webhooks' carves a clear niche, but the sibling skill setup-zoom-websockets (referenced in the body) represents a closely related trigger territory — a user asking to 'set up Zoom events' could plausibly mean either. Fits score 4 ('mostly distinct; minor overlap risk with closely related skills'), below score 5 because the boundary with the websockets skill is not drawn in the description itself.