Conciseness

The body is brief and checklist-like rather than verbose, but roughly a third of it is padding: the 'Use this skill when / Do not use this skill when' sections ('Working on cpp pro tasks or workflows', 'The task is unrelated to cpp pro') and the generic Instructions add no information beyond the frontmatter description, and the Focus Areas restate C++ knowledge Claude already has (RAII, Rule of Zero, const correctness). It is below anchor 4 because several sections could be cut entirely without losing value, but not 'severely verbose' as at anchor 2's explanatory padding.

Actionability

Some concrete guidance exists — named tools ('perf and VTune', 'Google Test or Catch2', 'AddressSanitizer/ThreadSanitizer', '#pragma once') and specific practices ('Leverage STL algorithms over raw loops', 'Follow the Rule of Zero/Three/Five') — but there is no executable code, no commands (not even a sanitizer or CMake flag), and the Instructions section is pure abstraction ('Clarify goals', 'Apply relevant best practices'). For a code-writing skill, that lands between the vague-hints of 2 and the concrete-but-gapped 4.

Workflow Clarity

The numbered 'Approach' list reads as a sequence but its items are simultaneous preferences, not ordered steps, and validation exists only implicitly ('validate outcomes', 'ASan/TSan clean output') with no checkpoint telling Claude when or how to verify. This matches anchor 3 — steps listed but checkpoints missing or implicit — rather than 4, whose sequence includes concrete verification commands.

Progressive Disclosure

The single reference to deeper material — 'If detailed examples are required, open `resources/implementation-playbook.md`' — is dangling: no resources/ directory or playbook file exists in the bundle, so navigation to detailed content fails entirely. Combined with boilerplate sections that belong at the description level being inlined, this matches anchor 2's 'minimal structure... references are buried' rather than 3, where references are at least present and functional.

Specificity

Names the domain and several concrete capability areas — 'RAII, smart pointers, and STL algorithms', 'templates, move semantics, and performance optimization', 'C++ refactoring, memory safety' — which go beyond generic claims. It falls short of a 5 because these are capability categories rather than discrete, comprehensive actions (e.g., no mention of build systems, testing, or debugging tasks it performs).

Completeness

Explicitly answers both: what — 'Write idiomatic C++ code with modern features, RAII, smart pointers, and STL algorithms. Handles templates, move semantics, and performance optimization' — and when — 'Use PROACTIVELY for C++ refactoring, memory safety, or complex C++ patterns', with concrete trigger phrases. It clearly matches the anchor 5 example structure; no anchor fits better.

Trigger Term Quality

Includes natural phrases a user would plausibly say: 'C++ refactoring', 'memory safety', 'complex C++ patterns', 'performance optimization'. A few common variations are missing (e.g., 'modernize C++', specific standard names like C++17/C++20), so it does not reach comprehensive coverage at 5.

Distinctiveness Conflict Risk

The C++ niche is clear and triggers mention C++ explicitly, keeping conflict risk low. 'Memory safety' and 'performance optimization' are also natural triggers for other languages' skills (e.g., Rust, general profiling), so there is minor overlap risk rather than the minimal risk of a 5.