Conciseness

The body is mostly efficient — decision trees and checklists carry real operational weight — but several sections explain knowledge Claude already has: the runtime-error tree spells out that a TypeError means an undefined value, and the Safe Fallback Patterns section shows generic default-config/empty-state TypeScript that is standard knowledge. It could be tightened without losing value, matching anchor 3 rather than the leaner anchor 4.

Actionability

Most guidance is executable: specific commands ("npm test -- --grep", "git bisect run ..."), a copy-paste regression test example, and concrete branch-by-branch actions in the triage trees. Minor gaps remain — some directives are abstract ("Ask: 'Why does this happen?' until you reach the actual cause") and commands are npm-specific with a substitution note — so it does not reach fully copy-paste-ready anchor 5.

Workflow Clarity

The six-step triage checklist is clearly ordered with an explicit "Do not skip steps" instruction, YES/NO branch decision trees, feedback loops for non-reproducible bugs (retry under load, isolate, compare environments), an explicit verification step ("RESUME only after verification passes"), and a final checklist. This matches the anchor for clear sequence with explicit validation, error-recovery loops, and checklists.

Progressive Disclosure

The skill is a single file with no bundle, and its 11 sections are clearly headed and easy to navigate, with no nested references. However, at ~295 lines, content such as the Error-Specific Patterns triage trees and Safe Fallback code examples could arguably live in one-level-deep reference files, and the cross-reference to "the test-driven-development skill's Discover the Stack First section" is a dangling pointer outside the bundle — minor organization gaps consistent with anchor 4.

Specificity

The description names the domain ("systematic root-cause debugging") and 1-2 concrete actions ("finding and fixing the root cause"), matching the anchor for naming the domain with a couple of concrete actions. It does not list several distinct specific actions (as in "Extract text, fill forms, merge documents"), so it falls short of anchor 4.

Completeness

It clearly answers both what ("Guides systematic root-cause debugging... finding and fixing the root cause") and when, with two explicit "Use when..." clauses containing concrete trigger phrases. Not below 5 because both questions are answered explicitly with concrete triggers, not merely implied.

Trigger Term Quality

It includes natural phrases users would actually say — "tests fail", "builds break", "something that worked yesterday broke", "unexpected error" — giving good keyword coverage. Common variations like "bug", "crash", "exception", or "stack trace" are missing, so it does not reach comprehensive anchor 5.

Distinctiveness Conflict Risk

The failure-triggered framing (broken tests/builds/regressions) carves a mostly distinct niche with minor overlap risk against closely related skills (e.g., testing or code-review skills). The very broad clause "or you encounter any unexpected error" slightly raises conflict risk, keeping it below anchor 5.