Conciseness

Noticeably verbose across several padded sections: 'Common Investigation Commands' restates pytest flags (-vv, -s, -x, --lf, --durations) and pdb/git basics Claude already knows, 'Tips for Effective Analysis' is generic advice ('Git history is your friend', 'Don't assume—test your hypotheses'), and Section 4 inlines a pattern catalog (API Signature Change, Return Type Change) that duplicates references/failure-patterns.md. Not 1 because much of the content (bisect workflow, report format, likelihood ranking) is genuinely non-obvious and useful; not 3 because the duplication and known-material padding spans multiple sections of a ~550-line body.

Actionability

Fully executable throughout: copy-paste git bisect sequences, git log -S searches, pytest invocations, fixture/mock debugging snippets, a complete report template with evidence and likelihood fields, and three worked example workflows. Not 4: the examples are concrete and copy-paste ready, covering the common cases (signature change, flaky test, dependency update) rather than leaving minor gaps.

Workflow Clarity

Six clearly sequenced steps (gather info → analyze errors → identify changes → match patterns → report → verify) with an explicit validation step and an error-recovery feedback loop: 'If fix doesn't work: 1. Review alternative hypotheses 2. Gather more information 3. Expand investigation'. The report template also mandates alternative hypotheses with likelihoods. Not 4: verification checkpoints and the retry-on-failure loop are explicitly stated, matching the top anchor; no destructive/batch cap applies since this is read-only investigation.

Progressive Disclosure

The reference file exists and is clearly signaled twice ('See [failure-patterns.md](references/failure-patterns.md)'), but the body inlines a four-pattern catalog that substantially duplicates the bundle file's content, and the full report template is embedded inline within step 5. Not 2 because references are clearly signaled and the body has real section structure; not 4 because content that clearly belongs in the separate file is duplicated in the body instead of deferred to it.

Specificity

Lists multiple specific concrete actions with comprehensive coverage: 'analyzing code changes, error messages, and test dependencies', 'Analyzes git diffs, stack traces, test output, and dependency changes to produce structured markdown reports ranking likely causes'. Inputs, analysis techniques, and output format are all explicitly named. Not 4: coverage of actions spans input gathering, multiple analysis methods, and a concrete deliverable, matching the comprehensive anchor rather than leaving gaps.

Completeness

Explicitly answers both what ('Locate root causes of failing regression tests by analyzing... to produce structured markdown reports ranking likely causes') and when, twice, with concrete trigger phrases ('Use when regression tests start failing after code changes, investigating test failures in CI/CD, debugging flaky tests...'). Not 4: the 'when' is fully explicit with multiple concrete trigger scenarios, matching the top anchor exactly.

Trigger Term Quality

Good keyword coverage with natural phrasings users would say: 'find why tests are failing', 'debug regression failures', 'investigate test breakage', 'analyze failing test suites', plus 'flaky tests' and 'CI/CD'. Not 5: a few common variants are missing (e.g., 'tests stopped passing', 'build failing', framework-specific phrasings); not 3 because multiple natural synonyms and trigger phrasings are present rather than a few generic keywords.

Distinctiveness Conflict Risk

Clear niche (regression test failures, root-cause analysis with ranked likelihoods) with distinct triggers, but 'investigating test failures in CI/CD' and general debugging phrasing could overlap with a generic debugging or CI-troubleshooting skill. Not 5 due to this minor overlap risk with closely related skills; not 3 because the regression-specific framing and trigger set are well-differentiated.