Conciseness

The body is mostly tight, high-signal tables (Quick Reference, Common Mistakes, Anti-Patterns) with details correctly delegated to 12 reference files, but includes a few explanations Claude already knows — 'Security in Go follows the principle of defense in depth… vigilance is still required' and the STRIDE acronym expansion — that could be trimmed. Not a 3 because padding is minor; not a 5 because the Overview paragraph, persona/thinking/orchestration preamble, and known-concept expansions spend tokens without adding skill-specific value.

Actionability

Concrete, executable guidance is present throughout — 'go tool gosec ./...', 'go tool govulncheck ./...', 'go test -race ./...', 'go test -fuzz=Fuzz', and named stdlib solutions like 'crypto/subtle.ConstantTimeCompare', 'os.Root', 'filepath.IsLocal + filepath.Rel' — plus a documented decision-comment convention. Not a 5 because the vulnerability-fix guidance in the body is mostly one-line table entries; the copy-paste-ready fix examples live only in the reference files.

Workflow Clarity

Modes (Review/Audit/Coding) are clearly defined, 'Research Before Reporting' is a numbered 4-step sequence acting as a validation gate on findings, and audit-mode fan-out with per-fix worktree isolation and DREAD scoring is well specified. Not a 5 because there is no explicit re-verify step after a fix (e.g., re-run gosec/-race to confirm remediation) in Coding mode; not a 3 because checkpoints (trace data flow, check upstream validation, severity-adjust-not-dismiss) are explicit rather than missing.

Progressive Disclosure

The body is a genuine overview hub — every one of the 12 referenced files (cryptography.md, injection.md, filesystem.md, network.md, cookies.md, third-party.md, memory-safety.md, secrets.md, logging.md, threat-modeling.md, architecture.md, checklist.md) exists in ./references/, is linked with a one-line description, and is exactly one level deep with no nested-reference chains. Navigation is easy and content is appropriately split.

Specificity

The description lists many specific concrete capabilities and tools — 'injection (SQL, command, XSS)', 'path traversal, SSRF and HTTP security headers, cookies, secrets management, memory safety, PII in logs, STRIDE/DREAD threat modeling, plus gosec SAST, race detection, and fuzz testing' — with comprehensive coverage of the Go security domain and no vague filler.

Completeness

It explicitly answers 'what' ('Security best practices and vulnerability prevention for Golang — injection … plus gosec SAST, race detection, and fuzz testing') and 'when' ('Apply when writing, reviewing, or auditing Go code for security, or when touching crypto, file or network I/O, secrets, user input, or authentication'), with concrete trigger phrases and an explicit negative boundary.

Trigger Term Quality

It covers the natural terms a user would actually say — 'security', 'SQL injection', 'XSS', 'crypto', 'secrets', 'path traversal', 'SSRF', 'audit' — plus synonyms ('Golang' and 'Go code') and tool names (gosec, govulncheck), matching the comprehensive-with-synonyms anchor.

Distinctiveness Conflict Risk

The niche is unambiguous (Go security), and it actively disambiguates from overlapping skills — 'Not for non-exploitable defensive bugs … (→ See samber/cc-skills-golang@golang-safety skill), dependency vulnerability scanning with govulncheck …, or wiring security scanners into CI pipelines' — minimizing wrong-skill triggering.