Conciseness

The body is largely efficient — no padding explaining what substitution is at length, and the repeated "Expected with 10 args / Expected with 0 args" annotations are functional test fixtures rather than filler. Not 5 because there are minor instances that could be trimmed: the fact that reference files are not substituted is stated twice in the body ("Reference files are NOT subject to substitution" and again in the Correct Pattern section), and the inspect output block enumerates 13 captured variables when a representative subset plus a pointer would do.

Actionability

Fully executable guidance throughout: exact invocation commands ("/example-argument-substitution CANARY_A CANARY_B ..."), concrete code examples with literal expected corruption, a mermaid routing diagram, and copy-paste-ready action output templates. The common cases (greet, farewell, inspect, empty/unknown action) are all covered with specific outputs.

Workflow Clarity

Clear sequenced workflows with explicit validation: the 4-step usage procedure ends in "Compare... Check whether output matches", and the 7-step add-a-test procedure is a full feedback loop (hypothesis → run → observe → record finding → only then apply), enforced by "Do not document any pattern as safe without completing all 7 steps." This matches the score-5 anchor with error-recovery loops; no destructive or batch operation is involved, so no cap applies.

Progressive Disclosure

Scored against the actual bundle: one reference file (references/argument-substitution-reference.md) exists, is one level deep, contains no nested references, and is clearly signaled at the end of the body with its scope stated ("All substitution variables, pitfall table, and verified escape evidence"). The demonstration content that remains inline must be there by design — substitution only applies to the SKILL.md body, which is the very behavior under test — so the split is appropriate rather than monolithic.

Specificity

The description lists four concrete capabilities — "demonstrates capture-block pre-declaration, XML tag referencing, unintentional variable corruption in code blocks, and correct placement of shell examples in reference files" — giving comprehensive, non-generic coverage of what the skill does. Not score 4 because there is no noticeable gap in coverage for this domain; not below 5 because every action named is concrete rather than abstract.

Completeness

Both what and when are explicit: what — "Test harness for Claude Code skill argument substitution — demonstrates..."; when — "Use when verifying substitution behavior before applying a pattern to other skills, testing how arguments flow from skill invocations, or understanding the pre-declaration and reference file pattern". This matches the score-5 anchor exactly with concrete trigger phrases; score 4 would require a less explicit 'when', which is not the case.

Trigger Term Quality

Good keyword coverage with natural phrases like "argument substitution", "reference files", "skill invocations", and the greet/farewell/inspect action names. Not 5 because some natural variations users might say are missing (e.g., "$ARGUMENTS", "positional arguments", "skill arguments"); not 3 because coverage goes well beyond a couple of generic keywords.

Distinctiveness Conflict Risk

"Test harness for Claude Code skill argument substitution" is a clear niche with distinct triggers (substitution verification, pre-declaration pattern, reference-file placement) unlikely to fire for unrelated skills. Not 4 because no meaningful overlap with other skill domains exists; the scope is tightly bounded to skill-authoring internals.