Conciseness

The body is largely lean — concrete Grep/Glob patterns, a compact constraints list, and a pointer-style output section — but "When to Use This Skill" duplicates the frontmatter description, and the EARS quick-reference table partially duplicates references/ears-format.md. Not 5: these sections could be trimmed; not 3: there is no concept-explaining padding of the kind Claude already knows.

Actionability

Concrete guidance throughout: exploration patterns like "Grep('@app\.route|@router\.|router\.get|router\.post', include='*.py')", a concrete output path "specs/{project_name}_reverse_spec.md", an EARS pattern table with examples, and MUST/MUST-NOT constraints. Not 5: the tool calls use pseudo-syntax ("Glob('**/*.py', exclude=[...])") rather than executable invocations, and the output template defers structure to a reference file.

Workflow Clarity

The five-step Scope→Explore→Trace→Document→Flag sequence includes an explicit validation checkpoint with a feedback loop: "If key entry points, configuration files, or core modules remain unread, continue exploration before writing documentation", plus a checklist reference. Not 5: only one checkpoint — the Document/Flag steps lack verification that each observation has code evidence, though the constraints section partially covers it.

Progressive Disclosure

The Reference Guide table signals each of the four references with a "Load When" condition (e.g., "Starting exploration, Glob/Grep patterns" → references/analysis-process.md), all files exist and are one level deep, and quick-reference content inline is appropriately split from full detail in references. This matches the top anchor: clear overview, well-signaled one-level-deep references, easy navigation.

Specificity

"extracts specifications from existing codebases" plus "map code dependencies, generate API documentation from source, identify undocumented business logic, figure out what code does, or create architecture documentation from implementation" lists multiple specific concrete actions with comprehensive coverage of the reverse-engineering niche. Not 4: coverage extends beyond several actions to span dependencies, API docs, business logic, behavior, and architecture.

Completeness

Clearly answers what ("extracts specifications from existing codebases", "map code dependencies, generate API documentation...") and when ("Use when working with legacy or undocumented systems, inherited projects, or old codebases with no documentation") with concrete trigger phrases. Not 4: both halves are explicit and specific, matching the top anchor exactly.

Trigger Term Quality

"reverse engineer, old codebase, no docs, no documentation, figure out how this works, inherited project, legacy analysis, code archaeology, undocumented features" covers natural phrases plus synonyms users would actually say. Not 4: the trigger list is comprehensive, including colloquial variants ("no docs", "figure out how this works") rather than missing common ones.

Distinctiveness Conflict Risk

"Reverse-engineering specialist" is a clear niche with distinct triggers ("code archaeology", "inherited project"), but broad phrases like "figure out what code does" and "understand codebase" (in metadata triggers) overlap with general code-exploration and code-review skills. Not 5: minor overlap risk remains; not 3: the niche is far more distinct than "Works with document files".