Conciseness

The body is largely efficient — the workflow, constraints, and code example all earn their tokens — but two sections are trimmable: the persona opener 'Senior Go developer with deep expertise in Go 1.21+...' and the 'Knowledge Reference' keyword list, which restates terms Claude already knows and largely duplicates the frontmatter description/triggers. This fits the 4 anchor (minor instances that could be trimmed) rather than the 5 anchor where every token earns its place.

Actionability

Guidance is fully executable: exact commands ('go vet ./...', 'golangci-lint run', '-race' flag) and a complete, copy-paste-ready Go example demonstrating context cancellation, %w error wrapping, and channel-based error propagation, with the key properties stated ('bounded goroutine lifetime via ctx... no goroutine leak on cancellation'). This matches the 5 anchor; it is not the 4 anchor because no key detail is missing.

Workflow Clarity

The six-step Core Workflow is clearly sequenced with three explicit validation checkpoints and proceed-gates: 'run go vet ./... before proceeding', 'fix all reported issues before proceeding', and 'confirm race detector passes before committing'. This matches the 5 anchor (explicit validation steps and feedback-loop gating); the 4 anchor would lack one of these checkpoints.

Progressive Disclosure

The ~110-line body is a true overview: a Reference Guide table routes five topics to references/concurrency.md, interfaces.md, generics.md, testing.md, and project-structure.md with explicit 'Load When' conditions. Verified against the actual bundle: all five files exist and contain no nested references, so navigation is one level deep and well signaled — the 5 anchor.

Specificity

The description lists multiple concrete action clusters with named technologies — 'Implements concurrent Go patterns using goroutines and channels', 'designs and builds microservices with gRPC or REST', 'optimizes Go application performance with pprof', 'enforces idiomatic Go with generics, interfaces, and robust error handling'. Coverage spans implementation, architecture, performance, and style, matching the comprehensive 5 anchor rather than the 4 anchor's 'minor gaps'.

Completeness

Both questions are explicitly answered: what ('Implements concurrent Go patterns... designs and builds microservices... optimizes... enforces idiomatic Go') and when ('Use when building Go applications requiring concurrent programming, microservices architecture, or high-performance systems. Invoke for goroutines, channels, Go generics...'). This mirrors the 5 anchor's structure with concrete trigger phrases.

Trigger Term Quality

Triggers include natural phrases users would say — 'goroutines, channels, Go generics, gRPC integration, CLI tools, benchmarks, or table-driven testing' — plus 'concurrent programming, microservices architecture'. Good coverage, but common variations like 'Golang', 'write Go code', or 'REST API' are missing, so it fits the 4 anchor rather than the 5 anchor's comprehensive synonym coverage.

Distinctiveness Conflict Risk

The niche is clear and the triggers (goroutines, channels, Go generics, gRPC, table-driven testing) are Go-exclusive vocabulary that would not fire for other language skills. This matches the 5 anchor's 'clear niche with distinct triggers; minimal conflict risk' rather than the 4 anchor's minor overlap with closely related skills.