Conciseness

Lean and efficient throughout: short sections of project-specific rules with no explanation of concepts Claude already knows (no React/Relay primers, no padding). Every token carries a project-specific instruction, matching the 5 anchor; it is clearly above the 4 anchor's 'minor instances of over-explanation'.

Actionability

Names exact, executable targets: 'useAgentDataChangeFetchKey from @phoenix/hooks in the query owner', 'handle.agentRoute metadata in js/app/src/Routes.tsx' with field-level detail ('label', 'description'), and 'encode it in route params or search params'. It sits between anchors: mostly executable with minor gaps (4) rather than fully copy-paste-ready (5) — phrases like 'use the available browser tooling to verify' and 'preserve the relevant URL state' give direction without a concrete example or command.

Workflow Clarity

An explicit starting step ('Before starting work, explore js/app/src/components/ and js/app/package.json… then follow these rules') plus scenario-conditioned rules and a verification section give a clear structure with most checkpoints present (4). Not a 5 because it is a rule collection rather than a sequenced workflow — there are no explicit feedback/recovery checkpoints — and not a 3 because the per-section when/what pairs are unambiguous and validation guidance ('use the available browser tooling to verify the UI looks correct', 'check its usages across the app') is present.

Progressive Disclosure

A concise overview body with a 'when to read' table cleanly mapping all five real reference files (components.md, relay.md, accessibility.md, test-ids.md, resize-svg-logo-assets.md) to task conditions, references exactly one level deep (verified: reference files point only to the bundled script, not to further .md files), and out-of-scope areas delegated to sibling skills (phoenix-storybook, phoenix-design). Matches the 5 anchor's clear overview with well-signaled one-level-deep references.

Specificity

Lists several concrete actions — 'writing, reviewing, or modifying React components, TypeScript code, styles, or UI features' plus 'new components, UI changes, styling, accessibility fixes, form handling, or component refactoring' — matching the 'several specific actions; minor gaps' anchor. It falls short of the 5 anchor because the framing 'Frontend development guidelines' is slightly generic relative to 'multiple specific concrete actions; comprehensive coverage', and it is above the 3 anchor which expects only 1-2 concrete actions.

Completeness

Explicitly answers both: what ('Frontend development guidelines for the Phoenix AI observability platform') and when ('Use when writing, reviewing, or modifying…', 'Triggers on any frontend task…', 'Also use when the user asks about frontend conventions or component patterns'). Clearly matches the 5 anchor with concrete trigger phrases; the 4 anchor applies only when 'when' is less explicit.

Trigger Term Quality

Comprehensive natural-term coverage with synonyms: 'new components', 'UI changes', 'styling', 'accessibility fixes', 'form handling', 'component refactoring', 'frontend conventions', 'component patterns', plus concrete anchors like 'React', 'TypeScript', and 'js/app/ directory'. Not the 4 anchor because it goes beyond 'a few natural terms missing' — the enumerated trigger list and the 'any frontend task' catch-all cover the domain's common phrasings.

Distinctiveness Conflict Risk

Clear niche scoped to a named platform and directory ('js/app/'), with explicit boundary guidance diverting design-system rules to the 'phoenix-design' skill. Distinct triggers ('React components', 'TypeScript', 'data-testid'-adjacent a11y work) and minimal conflict risk, matching the 5 anchor; it is well above the 3/4 anchors' residual overlap concern.