Conciseness

The body is lean in style — terse code examples with one-line commentary, no tutorial prose — but at ~670 lines it extensively documents concepts Claude already knows well (error wrapping, worker pools, sync.Pool, strings.Join, functional options), with some redundancy (three join variants, 'Best: use standard library' restating the obvious). This matches anchor 3 ('mostly efficient but includes some unnecessary explanation or could be tightened') rather than anchor 4, because large sections restate standard Go knowledge that adds little beyond what Claude already has.

Actionability

Nearly all guidance is concrete, executable Go with copy-paste-ready patterns plus a real command cheatsheet (go vet, golangci-lint, go test -race) and a concrete .golangci.yml. It falls short of anchor 5 because many snippets depend on undefined helpers (db.FindUser, process(job), fetch(url)) and omit import blocks, making them illustrative templates rather than fully runnable code — 'mostly executable... with minor gaps'.

Workflow Clarity

As a reference/catalog skill there is no multi-step process to sequence; sections are clearly ordered (When to Activate, Core Principles, Error Handling, Concurrency, Interface Design, Package Organization, Struct Design, Performance, Tooling, Anti-Patterns) with a quick-reference idiom table. This earns anchor 4 ('good structure, minor gaps') rather than 5 because anchor 5's explicit validation checkpoints/feedback loops are absent — the closest analog, the tooling section, lists commands but never says when to run them or how to act on failures.

Progressive Disclosure

The body has real section structure and is scannable, so it is above anchor 2's 'minimal structure'. But the entire ~670-line catalog lives inline in SKILL.md with no references/ split — error handling, concurrency, linter configuration, and performance sections are each substantial enough to be separate files — which matches anchor 3 exactly: 'some structure but could be better organized; content that should be separate is inline'.

Specificity

The description names the domain ("Idiomatic Go patterns, best practices, and conventions for building robust, efficient, and maintainable Go applications") but the stated capabilities are generic category nouns rather than concrete actions — there is no parallel to 'extract text, fill forms, merge documents'. It sits between anchor 2 ('actions are minimal or generic') and anchor 3 ('domain and 1-2 concrete actions'), and the enumerated pattern/best-practice/convention categories keep it at 3 rather than 2.

Completeness

Both 'what' ("Idiomatic Go patterns, best practices, and conventions...") and 'when' ("Use when writing or reviewing Go code and idiomatic structure or conventions are in question") are explicitly present, so it clears the anchor-3 cap for missing triggers. It does not reach anchor 5 because the 'what' is broad and abstract rather than concrete trigger-linked capabilities, and the 'when' clause ('idiomatic structure or conventions are in question') is slightly stilted compared to the anchor-5 phrasing.

Trigger Term Quality

"Use when writing or reviewing Go code and idiomatic structure or conventions are in question" captures natural phrases users would say (writing/reviewing Go code, idiomatic, conventions, best practices). It falls short of anchor 5's comprehensive synonym/extension coverage — e.g. 'Golang', 'Go code review', 'Go style' — but beats anchor 3's 'missing common variations'.

Distinctiveness Conflict Risk

The Go-specific framing ("Go code", "Go applications", "idiomatic") carves out a clear niche with distinct triggers, matching anchor 5's 'clear niche with distinct triggers; minimal conflict risk'. The only overlap risk is with generic code-review skills when 'reviewing Go code' is said, but the explicit Go domain marker keeps that minimal, so it does not drop to anchor 4.