Conciseness

The body is short and mostly lean, but the intro paragraph ("Duplicate content from URL parameters, www vs non-www, or pagination dilutes ranking signals") and the first two Quick Reference bullets ("Canonical URLs tell search engines which version of a page to index", "Prevents duplicate content penalties") re-explain concepts Claude already knows. These are minor, compact instances of over-explanation that could be trimmed, matching the anchor at 4 rather than the 'some unnecessary explanation' level at 3.

Actionability

The body contains no code, commands, or concrete verification method: Check says only "Verify that this page has a canonical URL tag" without how, and Fix says "Add or correct the canonical URL tag in the head section" without showing the tag. The few concrete hints ("Use absolute URLs including protocol and domain", "head section") are high-level, fitting 'minimal concrete guidance; high-level hints but missing the specific steps to execute'. It is above 1 because some specifics (absolute URLs, self-referencing, head placement) are stated.

Workflow Clarity

The Check → Fix → Explain → Code Review sections give a rough sequence for a simple single-purpose task, but checkpoints are implicit: there is no method for verifying the rendered canonical (e.g. inspecting fetched HTML vs source), no criteria for what the 'correct preferred version' is, and no validate-after-fix step. This matches 'steps listed but validation gaps; checkpoints missing or implicit' rather than 4.

Progressive Disclosure

The bundle structure is textbook progressive disclosure: the body is a concise overview, and full implementation details, code examples, and framework guidance are clearly signaled in one place — "see references/rule.md" — which exists as a real, one-level-deep reference file containing the code example and detailed guidance. This matches 'clear overview with well-signaled one-level-deep references; content appropriately split'.

Specificity

The description names the domain (canonical URLs / SEO auditing) and one concrete action — "Verify the rendered HTML and HTTP response rather than relying only on source files" — but offers no further actions (check, fix, add tags), matching the '1-2 concrete actions, not comprehensive' anchor. It is not a 4 because there are not 'several specific actions', and not a 2 because the verification action is genuinely concrete rather than generic.

Completeness

Both halves are present: the 'when' is explicit ("Use when auditing metadata, crawlability, structured data, or indexability related to Set canonical URLs for all pages") and the 'what' is a concrete verification behavior ("Verify the rendered HTML and HTTP response rather than relying only on source files"). It falls short of 5 because the 'what' covers only a single verification action and the embedded rule title ("related to Set canonical URLs for all pages") reads as garbled template text rather than a clear capability statement.

Trigger Term Quality

Phrases like "auditing metadata, crawlability, structured data, or indexability" and "canonical URLs" are relevant, but the most natural user phrasings — "SEO", "duplicate content", "canonical tag", "rel=canonical" — are absent. This fits 'some relevant keywords but missing common variations or synonyms' rather than the good-coverage anchor at 4.

Distinctiveness Conflict Risk

The canonical-URL niche is identifiable, but the trigger list ("metadata, crawlability, structured data, indexability") is shared by virtually every SEO-audit skill, so sibling rules (lowercase paths, trailing slashes, meta tags) would fire on the same phrases. This matches 'somewhat specific but could still overlap with similar skills'; it is more specific than the generic overlap at 2 but lacks the distinct triggers needed for 4-5.