Conciseness

The body is dense with original project-specific rules and explains nothing Claude already knows (no 'what is git bisect' padding), but several passages are over-long and convoluted — the ~200-word regression-guard sub-rules covering shell bracket forms and negative assertions, and the reporter-environment probe paragraph. This is 'mostly efficient but could be tightened' rather than the minor-trimming of anchor 4.

Actionability

Guidance is fully executable for an instruction-only skill: concrete commands ("git status --short --branch -uall", "git diff <last-good>..HEAD -- <suspect path>", "grep -rn"), a fill-in hypothesis template ("I believe the root cause is [X] because [evidence]"), an exact output block, and a worked example of a testable hypothesis ("Stale cache in useUser at src/hooks/user.ts:42 because the dependency array is missing userId").

Workflow Clarity

The diagnostic workflow is clearly sequenced with explicit validation checkpoints and feedback loops: a numbered Runtime Evidence Ladder, hard-stop gates ("Same symptom after a fix is a hard stop"), confirm-or-discard with probe-driven re-orientation, and a red-green regression verification procedure. Bisect mode even sequences worktree safety checks before any bisect command.

Progressive Disclosure

The main file is an overview with mode-dispatch, and five specialized playbooks (durable-context, failure-patterns, ime-unicode, logging-techniques, rendering-debug) are one level deep, each referenced with an explicit activation trigger ("load references/logging-techniques.md before changing code"). All five referenced paths exist in references/, and nothing is nested deeper.

Specificity

"Finds root cause before any fix" names the diagnosis domain with one concrete action, but does not list several specific actions (e.g., bisect, targeted logging, sibling sweeps) that the skill actually performs. It fits anchor 3 rather than 4 because coverage of capabilities is thin in the description itself.

Completeness

The description explicitly answers both questions: what ("Finds root cause before any fix") and when ("Use when something errors, crashes, regresses, or used to work"), with concrete trigger phrases. It also adds negative scope ("Not for code review or new features"), which strengthens rather than weakens the explicit when-guidance.

Trigger Term Quality

"errors, crashes, regresses, or used to work" are natural phrases users would actually say, giving good keyword coverage. It misses a few common variations ("stack trace", "why broken", "not working") that only appear in the separate when_to_use field, so it is not anchor-5 comprehensive within the description text.

Distinctiveness Conflict Risk

The diagnose-before-fixing niche is distinct, and the explicit exclusions ("Not for code review or new features") sharply demarcate it from adjacent skills. Trigger terms like "regresses" and "used to work" point uniquely at regression diagnosis, matching the clear-niche anchor.