Conciseness

The body is dense and assumes competence (no explanation of Rust, cargo, or what unit testing is), but the unit-vs-`pdk-test` distinction is explained three times ("When to use this skill vs alternatives", Step 1's decision tree, and "When to graduate to `pdk-test`") and the `INIT_SLEEP` gotcha is fully repeated in both Step 5 and Troubleshooting. Fits the 4 anchor ("minor instances of over-explanation that could be trimmed"); not 5 because of this redundancy, not 3 because there is no padded conceptual explanation.

Actionability

Everything is copy-paste executable: exact commands (`mkdir -p src/tests`, `cargo test hello_world -- --nocapture`, `make test`), a concrete `UnitTestBuilder` skeleton, exact error strings ("no upstream registered for authority X") with diagnostic steps (`info!("calling {:?}", &config.service);`) and specific fixes. Matches the 5 anchor; not 4 because even edge cases (entrypoint naming, timer advancement) get executable fixes.

Workflow Clarity

A clearly sequenced Step 1–5 workflow with an explicit validation gate ("this test must pass before adding mocks, advanced config, or violations. If it fails, jump to Troubleshooting") and a cause/fix Troubleshooting section that provides feedback loops for every named failure mode. Matches the 5 anchor (explicit validation steps, error-recovery loops, plus a Pattern Index checklist); not 4 because checkpoints are explicit and no risky step lacks a verify-then-proceed condition.

Progressive Disclosure

Good structure: lean overview sections, a Pattern Index table, and a well-signaled one-level-deep pointer for the full API ("lives in `pdk-templates/templates/unit_testing.md`... Do not re-derive"). Falls short of 5 because the seven referenced `templates/*.rs` files (e.g., `templates/hello_test.rs`) are not present in this skill's bundle — no references/, scripts/, or assets/ directories exist — so their location is only implied; not 3 because the references that do exist are clearly signaled and the split between inline essentials and external detail is sound.

Specificity

The description lists multiple concrete actions spanning the whole task lifecycle — "wire up `src/tests/`", "build a first `UnitTestBuilder` test", "mock HTTP/gRPC upstreams with closures or `TraceBackend`", "factor reusable `TestConfig` helpers", "assert on responses / headers / violations", "troubleshoot init-sleep races, authority mismatches, and feature-gate skew" — matching the comprehensive-coverage anchor; it is not 4 because no meaningful capability gap remains.

Completeness

It explicitly answers both questions: the "what" is the full first sentence of concrete capabilities, and the "when" is an explicit "Use whenever the user mentions..." clause with concrete trigger phrases — the exact 5 anchor. Not 3 because the when-clause is present, not 4 because it is fully explicit rather than weakly implied.

Trigger Term Quality

Trigger coverage is comprehensive and natural: phrasings a user would actually say ("test my policy", "how do I mock an upstream in pdk-unit", "why is my policy timer not firing in tests") alongside command forms ("cargo test PDK") and API identifiers (`UnitTestBuilder`, `with_entrypoint`, `TraceBackend`). Not 4 because both synonyms and technical variants are present with nothing obvious missing.

Distinctiveness Conflict Risk

A clear niche (unit-testing Omni Gateway PDK policies, in-process via `UnitTestBuilder` in `src/tests/`) with triggers unique to it, plus explicit disambiguation routing siblings ("For scaffolding / build / publish see `develop-pdk-policy`"). Not 4 because the overlap risk with the pdk-test integration framework and develop-pdk-policy lifecycle skills is actively resolved by routing statements rather than merely minor.