Conciseness

The body is mostly lean, project-specific convention (naming shape, assertion message format, nextest filter expressions) rather than general Rust knowledge, e.g. 'cargo clippy --all-features --all-targets --workspace --no-deps' and the `<subject>_<case>[_<variant>]` shape. A few generic platitudes Claude already knows ('Aim for high test coverage but prioritize test quality over quantity', 'Follow the same code quality standards in test code as in production code') keep it below the lean anchor 5, but there is no padded explanation of concepts — well above anchor 3's 'some unnecessary explanation'.

Actionability

Concrete, executable guidance dominates: exact clippy/cargo-doc commands, 'cargo nextest run -E \'test(<subject>_)\'', copy-paste assertion examples ('value.expect("should contain a valid configuration")'), the json! bad/good pair, and a concrete before/after test-naming example. Not 5 because some directives remain abstract ('Consider using parameterized tests', 'Database seeding can be performed using yarn commands in the project's package.json' — no actual command) and the naming example bodies are elided with `/* … */`.

Workflow Clarity

This is a conventions catalog, not a sequenced process: verification checkpoints exist (clippy 'to detect issues', cargo doc, 'run the complete test suite') but are never assembled into a workflow (write test → run nextest → clippy → fix → re-run), and no error-recovery loop is described, matching anchor 3's 'checkpoints missing or implicit'. It is not 2 — sections are coherent and each directive is well-defined — and not 4 since no explicit sequence ties test writing to verification. No destructive/batch operations are involved, so the cap-at-3 rule for missing validation does not apply.

Progressive Disclosure

A single self-contained file with no references/, scripts/, or assets/ bundle; sections are well-organized and the ~115-line scope is reasonable to keep inline, so there is no monolithic wall or buried-reference problem. Minor gap: the Test Naming section (~35 lines, the longest) could live in a reference file, which keeps it at anchor 4's 'minor organization gaps' rather than 5's ideal split.

Specificity

The description names the domain ('HASH Rust testing strategy') and a couple of concrete activities in the trigger clause ('writing Rust unit, integration, or snapshot tests, or choosing assertion and test-organization patterns'), but the 'what' is a bare label and coverage is incomplete — test naming conventions, verification commands, and test design guidance (half the body) are unmentioned. This matches the anchor 'Names domain and 1-2 concrete actions, but not comprehensive' better than 4, whose examples list several specific capabilities of the skill itself.

Completeness

Both parts are present: 'HASH Rust testing strategy' (what) and an explicit 'Use when writing Rust unit, integration, or snapshot tests, or choosing assertion and test-organization patterns' (when). Not 5 because the 'what' is a cryptic label — 'HASH' is unexplained and the description never states what the strategy covers (naming conventions, assertion standards, verification) — and not 3 because the 'when' is explicit and specific, not merely implied.

Trigger Term Quality

Natural terms a user would say are present: 'Rust', 'unit', 'integration', 'snapshot tests', 'assertion', 'test-organization patterns'. It falls short of the 5 anchor (comprehensive synonyms/variants) because common phrasings like 'test naming', 'cargo test', or 'clippy' — significant parts of the skill — are missing, while exceeding anchor 3's 'some relevant keywords' level.

Distinctiveness Conflict Risk

The Rust-testing niche with triggers like 'snapshot tests' and 'assertion patterns' is mostly distinct with only minor overlap risk against a general Rust-development or code-review skill. The unexplained 'HASH' prefix slightly muddies identity, keeping it below the clear-niche anchor 5.