Conciseness

Each section is individually tight, but the accessible-name computation order (aria-labelledby, then aria-label, then text) is stated three times (Quick Reference, Check, Fix), the aria-expanded point appears in four sections, and the 'Code Review' paragraph is generic boilerplate ('Flag exact elements, roles, labels, focus behavior, or keyboard interactions...') that could be trimmed. Mostly efficient with unnecessary repetition to tighten fits anchor 3; it is not 2 because no section teaches basic concepts Claude doesn't know at length.

Actionability

The Check section gives an ordered, attribute-level procedure ('check aria-labelledby first, then aria-label, then visible text content') and Fix gives a concrete 4-step decision list with specific attribute remedies (e.g., 'add aria-label=\'Descriptive name\'', 'use aria-labelledby referencing the most descriptive element\'s id'). It is not 5 because no inline markup example or automated-check command (e.g., an axe selector) appears in the body — the executable example is deferred to the reference file, which is acceptable for an instruction-only skill but leaves minor gaps.

Workflow Clarity

The Check-then-Fix structure forms a clear sequence with an ordered fix decision procedure, appropriate for a simple single-purpose non-destructive skill. It is not 5 because verification is only mentioned in passing ('note how to verify the fix with browser accessibility tooling or assistive tech') rather than given as an explicit validation step in the workflow, and the operational order of the six sections (Quick Reference through Code Review) is left implicit.

Progressive Disclosure

The body is a clear overview with a well-signaled, verified, one-level-deep reference ('see references/rule.md'), which exists and appropriately holds the code example, ARIA property table, and verification steps. It is not 5 because the pointer mislabels the reference's contents (promising 'framework-specific guidance' that rule.md does not contain) and several points (Why It Matters, required ARIA properties) are duplicated between body and reference rather than cleanly split.

Specificity

The description names the domain precisely ('custom tree widgets built with role=\'tree\', role=\'treeitem\', and role=\'group\'') but states no concrete actions — what the skill does (ensuring accessible names on tree items) is never mentioned. This matches anchor 2 ('names the domain but actions are minimal or generic') rather than 3, which requires 1-2 concrete actions.

Completeness

A 'when' clause is present ('Use when applies to custom tree widgets...') but the 'what' is completely absent — nothing states the skill checks or fixes accessible names for tree items. This matches anchor 2 ('only \'when\' is present without \'what\'', e.g. 'Use when working with documents'); it is not 3 because anchor 3 requires a clear 'what'. The phrasing 'Use when applies to' is also grammatically malformed.

Trigger Term Quality

Natural phrases like 'file explorers', 'nested navigation menus', 'org charts', and 'expanded or collapsed' are present, but the most natural terms a user would say for this need — 'accessibility', 'screen reader', 'ARIA', 'accessible name' — are entirely missing. Good relevant keywords with common variations missing fits anchor 3; it is not 4 because the absent terms are the domain's primary vocabulary, not just a few extras.

Distinctiveness Conflict Risk

The role-scoped trigger ('custom tree widgets built with role=\'tree\', role=\'treeitem\', and role=\'group\'') gives a clear, distinct niche unlikely to fire for unrelated skills. It is not 5 because omitting the distinguishing 'accessible name' purpose leaves minor overlap risk with sibling ARIA tree-widget rules (e.g., treeitem keyboard interaction rules).