Conciseness

The body is lean and every section earns its tokens: the Rule states the pattern in one paragraph, the Why section is two sentences of rule-specific justification (why real links beat imperative navigation in this codebase's context), the How gives three code patterns plus bullet guidance, and the Review gives exact search strings. There is no padding or explanation of concepts Claude already knows, matching the 'lean and efficient; assumes Claude's competence' anchor.

Actionability

Guidance is fully executable: concrete JSX for all three common cases (`<Link to={`/items/${item.id}`}>`, `<Button asChild><Link to="/settings">`, `<a href={previewUrl} target="_blank" rel="noopener noreferrer">`), exact search patterns to run (`onClick={() => navigate`, `window.open`, `onAuxClick`), a named formatter (oxfmt), and a concrete verification matrix (normal click, Cmd/Ctrl-click, middle-click, Enter). This covers the common cases the way the level-5 anchor asks; level 4 would require minor gaps in the examples, and the only placeholder (`...` children) is the conventional, appropriate one.

Workflow Clarity

The Review section gives a clear sequence: search for candidates (`onClick={() => navigate`, `window.open`, `onAuxClick`), confirm each candidate is pure navigation before changing it, verify the DOM exposes an href, then test all click variants and run oxfmt plus focused tests — explicit checkpoints are present. It stops short of the level-5 anchor's explicit error-recovery loop ('if errors: fix and re-validate'), e.g., what to do when a candidate turns out to be a stateful workflow or when tests fail; the confirm-before-changing checkpoint is what holds it above level 3.

Progressive Disclosure

The skill is under 50 lines with no need for external reference files (none exist in the bundle), and the body is cleanly organized into well-labeled sections — Rule, Why, How, Review, Related Skills — each with a distinct role. The Related Skills cross-references (`client-side-routing`, `frontend-design`, `shadcn-ui`) are one level and clearly signaled, matching the simple-skill case where well-organized sections alone warrant the top score.

Specificity

The description names concrete capabilities: "adding or reviewing UI navigation", "preserve normal SPA behavior", "Cmd/Ctrl-click and middle-click new-tab semantics". It names several specific behaviors but does not enumerate the full range covered by the body (external links, accessibility, card overlays), which keeps it just short of the comprehensive coverage of the level-5 anchor. It is clearly above level 3 because it lists multiple concrete actions rather than only 1-2.

Completeness

It explicitly answers both questions with concrete trigger phrases: what — "so internal routes preserve normal SPA behavior plus Cmd/Ctrl-click and middle-click new-tab semantics" — and when — "Use when adding or reviewing UI navigation". This matches the level-5 good example structure (capability statement followed by an explicit 'Use when' clause with concrete triggers); level 4 would require the 'when' to be less explicit or specific.

Trigger Term Quality

Natural terms a frontend developer would say are present: "UI navigation", "internal routes", "SPA", "Cmd/Ctrl-click", "middle-click", "new-tab". A few common variations users might say are missing (e.g., "link", "anchor", "href", "make this clickable"), so it fits the 'good keyword coverage; a few natural terms missing' anchor rather than the comprehensive synonym coverage of level 5, while clearly exceeding the partial coverage of level 3.

Distinctiveness Conflict Risk

It occupies a clear niche — link/modifier-click semantics for SPA routes — with distinct trigger terms like "Cmd/Ctrl-click" and "middle-click new-tab" that no generic routing or UI skill would claim, so it is unlikely to trigger for the wrong skill. This fits the 'clear niche with distinct triggers; minimal conflict risk' anchor; the only conceivable overlap is with a general routing skill, which is too minor to drop to level 4.