Conciseness

Prose is lean (one sentence per pattern, then code) with no concept tutorials, but the ~310-line body inlines some boilerplate Claude already knows well (basic constructor injection, standard middleware skeleton, the 'Bad' mutable-model strawman). Not 3 — there is no real over-explanation; not 5 because a few sections could be trimmed or dropped without losing guidance value.

Actionability

Every section is complete, executable, copy-paste-ready C# covering the common cases: records, DI registration, async all the way (including Task.WhenAll), Options, Result, EF Core repository, middleware, minimal APIs, guard clauses, plus a concrete anti-pattern table. Matches the anchor-5 example fully.

Workflow Clarity

A reference/pattern-catalog skill rather than a multi-step process: the 'When to Activate' section plus self-contained, clearly headed pattern sections make application unambiguous, and no destructive/batch operations exist that would require validation checkpoints. Not 5 because there is no explicit ordering guidance (e.g., 'check the anti-pattern table first when reviewing').

Progressive Disclosure

Well-organized single-file structure with clear section headers and no broken or buried references (no bundle files exist, and none are strictly needed at this size). Not 5 because all content is inline with no layering — at ~310 lines, detailed reference material (e.g., full EF Core repository and middleware implementations) could move to references/ as the skill grows; not 3 because the structure and navigation are genuinely good.

Specificity

Lists several specific coverage areas ('conventions, dependency injection, async/await') alongside the domain, but they are framed as topics rather than concrete actions and include mild padding ('best practices for building robust, maintainable .NET applications'). Not 3 because it names more than 1-2 concrete items; not 5 because 'best practices' and 'robust, maintainable' are vague filler rather than concrete capabilities.

Completeness

Explicitly answers both what ('Idiomatic C# and .NET patterns, conventions, dependency injection, async/await') and when ('Use when writing or reviewing C# / .NET code — DI, async, or general conventions') with concrete trigger phrases. Matches the anchor-5 example structure exactly; no gaps that would justify 4.

Trigger Term Quality

Includes natural terms users would say — 'writing or reviewing C# / .NET code', 'DI', 'async' — with both the abbreviation and full form ('dependency injection'). Not 5 because common variations like 'ASP.NET', 'dotnet', or 'Entity Framework' are missing; not 3 because coverage goes well beyond a couple of generic keywords.

Distinctiveness Conflict Risk

Clear niche (C#/.NET) with highly distinct trigger terms, minimal conflict risk with other skills. 'general conventions' and 'best practices' introduce only trivial overlap, far less than the anchor-4 'minor overlap risk with closely related skills'.