Conciseness

The ~430-word body is pure directive content — "Spawn prp-core:root-cause-analyzer with the original report", "Do not publish a UNRESOLVED diagnosis as fact", "Read the created or updated issue back to verify the content" — with zero explanations of concepts Claude already knows and no padding. Every token earns its place, matching the level-5 anchor; level 4 would require identifiable trimmable over-explanation, which is absent.

Actionability

As an instruction-only skill it provides concrete, executable guidance throughout: explicit decision branches ("One clear match → use it", "Several plausible matches → ask the user", "No clear match → plan to create an issue"), a enumerated requirement list for the analysis, and an exact specification of the comment contents ("corrected problem statement, reproduction evidence, root cause or explicit condition, causal chain, fix boundary, regression proof, and remaining uncertainty"). It is not level 4 because all common cases (existing issue, no issue, duplicate, no GitHub access, --no-publish, --rewrite-body, UNRESOLVED, CONDITIONAL) are explicitly covered with concrete handling.

Workflow Clarity

Four clearly sequenced phases (resolve target → run analysis → reconcile duplicates → publish) with explicit validation checkpoints: a required regression check that "fails before the fix and passes after it", a post-diagnosis duplicate re-check, a stop-before-publication guard when GitHub access fails, and a read-back verification of the published artifact. Not level 4: checkpoints are explicit and complete, including error-recovery paths (UNRESOLVED handling, disabled publication treated as non-failure).

Progressive Disclosure

The body is under 50 lines, needs no external reference files (verified: no references/, scripts/, or assets/ exist in the bundle), and is organized into four well-labeled numbered sections with the delegation to prp-core:root-cause-analyzer clearly signaled. Per the simple-skill guideline, this earns the level-5 anchor; nothing that belongs in a separate file is inlined.

Specificity

"Diagnoses a bug, error, stack trace, regression, or unexplained behavior and publishes the evidence-backed root cause to GitHub" plus "commenting on the matching open issue or creating one when none exists" lists multiple concrete actions (diagnose, publish, comment, create) with comprehensive coverage of the skill's scope, in third-person voice. It clearly matches the level-5 anchor and exceeds level 4 because coverage is comprehensive rather than having minor gaps.

Completeness

It explicitly answers "what" (diagnose and publish an evidence-backed root cause to GitHub) and "when" ("Use when the user says 'debug this', 'find the root cause', provides a bug report or stack trace...") with concrete trigger phrases, matching the level-5 anchor exactly. It is not level 4 because the 'when' clause is fully explicit rather than improvable.

Trigger Term Quality

Natural trigger phrases include "debug this", "find the root cause", "provides a bug report or stack trace", "asks to investigate a GitHub issue", and "invokes /prp-debug", covering synonyms (bug, error, stack trace, regression, unexplained behavior) plus the literal slash-command name. This is comprehensive natural-term coverage, not the level-4 anchor where natural terms are missing.

Distinctiveness Conflict Risk

The niche is mostly distinct — evidence-backed root-cause analysis with durable GitHub publication — but the trigger "debug this" is broad enough to overlap with a general-purpose debugging skill, so minor overlap risk with a closely related skill remains. It is above level 3 (the domain and artifact are specific) but below level 5 because generic debugging phrases are not fully scoped to this skill's publish-the-finding behavior.