Conciseness

The body is lean throughout: eleven terse numbered steps with zero padding, listing header names ("CSP, HSTS, X-Content-Type-Options, frame-ancestors, Referrer-Policy") and checks without explaining concepts Claude already knows (e.g., what XSS or a session cookie is). This matches anchor 5 ('Lean and efficient; assumes Claude's competence; every token earns its place') with nothing to trim.

Actionability

Guidance is mostly executable with concrete anchors: named tools ("ZAP baseline", "npm audit", "pip-audit"), exact parameters ("next=", "return_url=", "redirect="), and an exhaustive SSRF target list ("loopback, private ranges, link-local, IPv6, decimal IPs, redirect-to-private, and DNS rebinding"). Minor gaps keep it below anchor 5: no example payloads for the XSS/injection steps ("HTML/script-like text", "SQL-ish and template-ish strings") and no ZAP invocation command.

Workflow Clarity

A clear 11-step sequence runs passive-to-active with inline verification cues ("confirm it renders inert", "Look for errors or behavior changes") and a termination checklist ("Each ASVS chapter in scope is marked tested, not applicable, or blocked"), matching anchor 4's 'clear sequence with most checkpoints present'. It is not anchor 5 because there are no explicit feedback loops or error-recovery steps; the destructive-operation cap does not apply since the skill is explicitly non-destructive and gates active tests behind approval.

Progressive Disclosure

The skill is under 50 lines with no bundle files and no content that belongs in separate references; sections (Procedure, Exit criteria) are well organized and external pointers (ASVS 5.0, WSTG) are one-line, one-level-deep links. Per the rubric's simple-skill guideline, this earns anchor 5 on well-organized sections alone.

Specificity

The description enumerates eight concrete vulnerability categories ("injection, XSS, SSRF, CSRF, open redirects, headers, secrets exposure, and rate limits") and names two governing frameworks (OWASP ASVS 5.0, WSTG), which is comprehensive coverage of the web security testing domain. This matches the anchor 'Lists multiple specific concrete actions; comprehensive coverage' rather than 4, since the enumeration spans the major web vulnerability classes with no obvious gaps.

Completeness

Both parts are explicit: the 'what' ("Run scoped, non-destructive web security checks guided by OWASP ASVS 5.0 and the WSTG, covering...") and the 'when' ("Use for security review of any web app within approved scope"). It does not reach anchor 5 because the 'when' offers a single trigger scenario rather than multiple concrete trigger phrases (e.g., pentest, audit, vulnerability scan), fitting anchor 4's 'when could be more explicit or specific'.

Trigger Term Quality

Natural terms users would say are present: "security review", "web app", and the vulnerability names XSS, CSRF, SSRF, and injection. It falls short of anchor 5 because common synonyms like "pentest", "vulnerability scan", "security audit", or "bug bounty" are missing, but it is clearly above anchor 3 since multiple genuinely natural keywords are covered.

Distinctiveness Conflict Risk

The niche is clear (scoped, non-destructive web app security testing) and distinguishable from general code-review skills, matching 'Mostly distinct; minor overlap risk with closely related skills'. It is not anchor 5 because the phrase "security review" is shared vocabulary with code-level security-review skills, creating minor conflict risk.