Conciseness

The body is a dense rulebook — a decision rule, a compact diagram, exact naming conventions, and six one-line anti-patterns — with no tutorial prose explaining known concepts. It falls short of anchor 5 only because the testing section's closing sentence ("Test the domain exhaustively with fast unit tests; test adapters against real infrastructure sparingly") restates the three per-layer bullets above it and could be trimmed.

Actionability

Concrete, executable guidance throughout: the decision rule ("Does it do I/O or run out-of-process?"), the dependency disqualification rule, exact naming conventions with real identifiers (MemberView, MemberDbo, request.asMember()), and a per-layer testing strategy. Below anchor 5 because no worked example of a port and its adapter is shown, leaving the central "Domain defines ports; adapters implement them" rule without a concrete illustration.

Workflow Clarity

There is no numbered multi-step sequence, but the core decision procedure is unambiguous and the skill involves no destructive or batch operations, so the validation cap does not apply. Below anchor 5 (and the simple-skill exception) because the design ordering — domain model first, then ports, then adapters — is only implied inside the "Premature Database Design" anti-pattern rather than presented as an explicit sequence.

Progressive Disclosure

A well-organized single-file skill with clear sections and no bundle files or external references; nothing is buried or nested. It misses anchor 5 because at roughly 82 lines it exceeds the under-50-line carve-out for reference-free skills, and the six-entry anti-pattern catalog is content that could reasonably live in a reference file; it is clearly above anchor 3 since the organization has no real gaps.

Specificity

The only explicit capability is the single action "Applies hexagonal (ports & adapters) architecture"; the concrete activities ("separating domain from infrastructure", "creating testable boundaries") live in the use-clause rather than as stated capabilities. This matches anchor 3 (domain named with 1-2 concrete actions, not comprehensive) — below 4 because no distinct list of capabilities is stated, above 2 because the domain is named precisely.

Completeness

It clearly answers "what" ("Applies hexagonal (ports & adapters) architecture") and explicitly answers "when" with a concrete "Use when..." clause listing trigger phrases, mirroring the anchor-5 example structure. Not 4, because the "when" is fully explicit rather than merely present with room for more specificity.

Trigger Term Quality

"ports", "adapters", "hexagonal", and "clean architecture" are terms users naturally say when they need this skill, giving good keyword coverage. It falls short of anchor 5's comprehensive coverage because sibling synonyms like "onion architecture" or "keep business logic framework-free" are missing.

Distinctiveness Conflict Risk

Hexagonal architecture is a clear niche with distinctive triggers (ports, adapters, hexagonal), so conflict risk is low. Minor overlap remains via "clean architecture" — a sibling concept that could belong to a separate skill — and the broad phrase "designing application structure", keeping it below anchor 5.