Conciseness

The body is efficient — mode detection as a table, terse test-category lists, one copy-paste bash block, and a structured output template — with no padding explaining concepts Claude already knows. Not 5: the 'Persona' section and the 'Workflow' section partially restate the intro and Mode A steps, so a few tokens could be trimmed.

Actionability

Guidance is fully executable: the HMAC-signing bash block is copy-paste ready, the output format is a fill-in template with exact fields ('Result: Expected | BUG | Unclear', 'Severity: BLOCKER | HIGH | MEDIUM | LOW'), Mode A enumerates six concrete test categories with example attacks per category, and the Troubleshooting section pairs each error with cause and solution. Not 4: concrete commands, templates, and worked examples cover the common cases, matching anchor 5.

Workflow Clarity

The three modes are clearly sequenced; Mode A gives a numbered procedure with an explicit per-test recording checkpoint ('Record every attempt with input, response, and resulting state', 'Record everything — even tests that don't find bugs') and a per-test classification step in the output format, plus error-recovery guidance in Troubleshooting. Not 5: minor validation gaps remain — no explicit pre-flight check that the API is reachable/smoke-testable before a full batch run, and no re-check loop after bugs are filed.

Progressive Disclosure

Structure is well organized — a rules table maps each concern to a file and impact level, references are clearly signaled and only one level deep — but every referenced bundle file ('rules/std-test-plan.md', 'rules/sec-auth.md', 'rules/sec-input.md', 'rules/edge-dedup.md', 'rules/edge-race.md', 'rules/rpt-bug.md', 'rules/_sections.md') is missing: the bundle contains no rules/, references/, scripts/, or assets/ directories at all. Scored against the actual bundle structure, the disclosure chain is broken — navigation points to nonexistent files — which is worse than anchor 4's 'minor organization gaps' and fits anchor 3's incomplete organization.

Specificity

The description lists multiple concrete, specific actions — 'Tests security boundaries, input validation, race conditions, deduplication, and malformed requests', 'systematically tries to break an application's API', 'Reports bugs with full reproduction details' — giving comprehensive coverage of the skill's capabilities. Not 4: coverage is broad and each action is concrete, not leaving minor gaps.

Completeness

Both questions are explicitly answered: what ('adversarial QA tester that systematically tries to break an application's API... Reports bugs with full reproduction details') and when ('Trigger on "break the API", "chaos monkey", ... or when a test plan defines API endpoints') with concrete trigger phrases. Not 4: the 'when' clause is not merely present but lists five concrete trigger phrases plus a contextual condition, matching anchor 5 exactly.

Trigger Term Quality

Natural trigger phrases are present and phrased as a user would say them: "break the API", "chaos monkey", "adversarial testing", "security test the endpoints", "test edge cases", plus the contextual condition "when a test plan defines API endpoints". Not 5: common synonyms like "fuzz", "negative testing", or "pen test" are missing, which anchor 4 ("a few natural terms missing") fits better than anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

The niche is distinct — 'chaos monkey' and 'break the API' clearly separate this from general QA or code-review skills. Not 5: broader phrases like 'test edge cases' and 'security test the endpoints' carry minor overlap risk with generic security-audit or endpoint-testing skills, fitting anchor 4 ('minor overlap risk with closely related skills').