Conciseness

The body is efficient overall, but the STRIDE letter/property table and the DFD element legend ("External entities (rectangles) — users, third-party services, admins") restate notation Claude already knows; the concrete examples (BFLA, billing exhaustion via paid downstream APIs) earn their place. Anchor 4 fits better than 3 (padding is minor) and better than 5 (known-concept restatement is present).

Actionability

Copy-paste-ready artifacts throughout: a Mermaid DFD example, the STRIDE-per-element table template ("Element: API Gateway" with L/M/H/C ratings), the abuse-case format with worked examples, the bad-vs-good mitigation table, and a full output-format markdown skeleton — specific examples cover the common cases.

Workflow Clarity

The four-question framing sequences Steps 1–4 explicitly, and Step 4 is dedicated validation with a coverage checklist ("every element in the DFD has a STRIDE table; every threat has a mitigation; every mitigation has an owner and a deadline") and feedback loops ("If you can't write the test, you don't have the mitigation, you have an intention"). Not a destructive/batch operation, so the cap does not apply.

Progressive Disclosure

A single-file skill (~215 lines) with well-organized sections and clearly signaled cross-references to sibling skills (`owasp-audit`, `api-audit`, `iam-audit`); no bundle files exist. Good structure with minor gaps — content like the detailed common-mitigation-patterns table and external book references could be split into a reference file, keeping it at anchor 4 rather than 5.

Specificity

"Run a structured threat-modeling session" plus the dash-list "STRIDE, attack trees, data flow diagrams, abuse cases" names several concrete outputs, but a single verb carries the action list and mitigation/validation steps are unstated — between anchors 4 and 5, closer to 4.

Completeness

Both are explicit: what ("Run a structured threat-modeling session ... STRIDE, attack trees, data flow diagrams, abuse cases") and when ("Use when the user mentions ... or needs strategic security thinking before code is written") with concrete trigger phrases — a direct structural match to the anchor 5 example.

Trigger Term Quality

"Use when the user mentions 'threat model,' 'threat modeling,' 'STRIDE,' 'attack tree,' 'abuse case,' 'data flow diagram,' 'DFD,' ..." comprehensively covers natural terms with synonyms (threat model/threat modeling, data flow diagram/DFD) and colloquial phrases ("what could go wrong"), matching the anchor 5 example.

Distinctiveness Conflict Risk

The design-time security niche is clear with signature triggers (STRIDE, attack tree, DFD), but "design review" and "what could go wrong" are broad enough to overlap with general review or architecture skills — minor overlap risk per anchor 4 rather than the minimal conflict risk of anchor 5.