Conciseness

Every line is instruction ('Mark each trust boundary crossed', 'Write one sentence with file:line and confidence') with zero concept explanations or padding; the skill assumes Claude's competence throughout. It is not score 4 because there is nothing that could be trimmed without losing information.

Actionability

The body gives concrete commands ('git log -L / git blame'), an explicit trace path (UI event → request → handler → data write → response → render), a classification taxonomy, an exact output format (file:line with CONFIRMED/SUSPECTED confidence), and a numeric stop rule (3 theories). Though instruction-only, the guidance is fully executable; it is not score 4 because no key execution detail is missing.

Workflow Clarity

A clearly sequenced 7-step procedure with an error-recovery feedback loop (step 7: stop after 3 failed theories and request more evidence), a verification standard (CONFIRMED requires a trace), and an Exit Criteria checklist. Not score 4: validation checkpoints are explicit, not implicit, and the operation is neither destructive nor batch so no cap applies.

Progressive Disclosure

The skill is under 50 lines with a single task and no external references needed, and content is organized into clear sections (Procedure, Exit criteria), satisfying the simple-skill exception. The 'fix-data-repair' and 'qa-recon-risk-map' mentions are cross-skill pointers, not buried or nested references, so there is no navigation burden.

Specificity

The description lists three concrete actions — 'tracing the full data and control path', 'asking why until reaching the decision that created the bad state', and 'checking history' — which comprehensively cover the root-cause task. It is not score 4 because there are no meaningful coverage gaps in the actions named.

Completeness

It explicitly answers both what ('Find the true root cause of a reproduced bug by tracing...') and when ('Use after reproducing and before planning any fix') with a concrete, checkable trigger condition. It is not score 4 because the when-clause is already explicit and specific to its workflow position, leaving nothing implicit.

Trigger Term Quality

Natural terms like 'root cause', 'bug', 'reproduced', and 'fix' are present and would be said by users needing this skill, but common variations such as 'debug', 'diagnose', 'regression', or 'why is this happening' are missing. It exceeds score 3 because keyword coverage is good, not merely partial.

Distinctiveness Conflict Risk

The niche — root-causing a reproduced bug after reproduction and before fix planning — is well-delineated and unlikely to fire for unrelated skills. It falls short of score 5 because 'bug' and 'root cause' are common debugging vocabulary, leaving minor overlap risk with closely related debugging/diagnosis skills.