Conciseness

The body (~25 lines) is lean with zero padding and no explanation of concepts Claude already knows — every line is either a trigger example, a rule name, or a checklist step. This matches anchor 5 ('lean and efficient; every token earns its place'); the body's problem is missing substance, not verbosity, so it does not fall to anchor 4.

Actionability

"Apply These Rules" lists bare rule identifiers (`routing-default`, `routing-aliases`, ...) with no content, file path, or location defining what each rule says, and no bundle files exist to resolve them. Checklist steps like "Rewrite vague preference descriptions with concrete task scopes" and "Validate routing behavior using trace-based checks" are high-level hints with no commands, examples, or config snippets — matching anchor 2 ('high-level hints but missing the specific steps to execute') rather than anchor 3, which requires some concrete guidance.

Workflow Clarity

The numbered 5-step "Execution Checklist" is a coherent sequence and ends with a validation step ("Validate routing behavior using trace-based checks"), but that checkpoint is implicit — no command, trace-check procedure, or error-recovery loop is given, and earlier steps lack any verification. This matches anchor 3 ('sequence present but checkpoints missing or implicit') rather than anchor 4, whose example includes executable validation commands.

Progressive Disclosure

The body is well-sectioned (When To Use / Apply These Rules / Execution Checklist) and short enough that a simple skill could score 5, but it references named rules (`routing-default`, `routing-aliases`, `routing-passthrough`, `routing-preferences`) that resolve to nothing — there are no references/, scripts/, or assets/ directories and no links or paths. These dangling references are not clearly signaled to any real file, matching anchor 3 ('references present but not clearly signaled') rather than anchor 4's 'references mostly clear'.

Specificity

The description names the domain ("Plano model routing and selection") and one concrete action ("Optimize"), then enumerates concrete topic areas ("provider defaults, model aliases, passthrough auth, and routing preference quality"). It does not list multiple distinct action verbs, so it falls between anchor 3 ('names domain and 1-2 concrete actions') and anchor 4 ('lists several specific actions') — the single verb plus topic enumeration keeps it at 3 rather than 4.

Completeness

Both parts are explicit: what — "Optimize Plano model routing and selection"; when — "Use for provider defaults, model aliases, passthrough auth, and routing preference quality." This matches anchor 4 (both present, 'when' could be more explicit): the when-clause lists trigger topics rather than concrete user situations like the anchor-5 example's "when the user mentions PDFs, forms", so it does not reach 5.

Trigger Term Quality

"model aliases", "passthrough auth", "provider defaults", and "model routing" are natural phrases a user tuning a router would actually say. It is good keyword coverage but missing common variations (e.g., "wrong model", "fallback", "cost"), matching anchor 4 rather than the comprehensive synonym coverage of anchor 5.

Distinctiveness Conflict Risk

"Plano" plus the routing/alias/passthrough-auth vocabulary carves out a clear niche with distinct triggers and minimal overlap with other skills, matching anchor 5. It is not generic enough to fall to anchor 4's 'minor overlap risk with closely related skills'.