Lean and efficient throughout — compact curl probes, a terse misconfig matrix, and a minimal HTML PoC; the brief opening framing on ACAO+ACAC severity earns its place as tactical context rather than concept padding. Not level 2 because nothing reads as filler.

Provides fully executable curl/bash probe commands, a copy-paste HTML exfil PoC, and named tools with concrete invocations (e.g. 'python corsy.py -u https://<TARGET>'). Not level 2 — no pseudocode or missing key details.

Clear numbered sequence (Detection → Matrix → PoC → Chains → Tools → OPSEC) culminating in an explicit Decision Gate checklist that validates pre-escalation and downgrades otherwise — a concrete feedback loop. Not level 2 because validation checkpoints are explicit, not implicit.

Self-contained single-file skill with well-organized sections and no nested/deep references; per the simple-skill guideline, well-organized sections with no need for external files score 3. The inline 'finding-protocol' pointer is a one-level cross-skill reference, not a deep nest.

Lists multiple specific concrete actions — "reflected origin, null origin, trusted-subdomain abuse, regex-validation bypass, and credentialed cross-origin data theft" — matching the score-3 anchor; it is not the vague single-action level 2.

The "what" is explicit and thorough, but there is no "Use when…" clause or equivalent trigger guidance; per the judging guidelines a missing explicit trigger caps completeness at 2. Not level 1 because the what is strong.

Includes core natural terms ("CORS", "cross-origin", "origin") but leans on jargon ("regex-validation bypass", "trusted-subdomain abuse") and omits common variations a user might say ("ACAO", "preflight"). Not level 3 because coverage is uneven, not level 1 because key terms are present.

Targets a clear niche (CORS misconfig exploitation) with distinct, non-overlapping triggers unlikely to fire for the wrong skill; matches the score-3 anchor.