Conciseness

The six-STRIDE-category table with verbatim Microsoft definitions (e.g., "illegally accessing and then using another user's authentication information, such as username and password") re-explains a classification Claude already knows, and the boundary/quote material could be tightened. It is mostly efficient — the steps, matrix, output template, and anti-patterns all earn their tokens — so it sits above the verbose 2-anchor but below the minor-trim 4-anchor.

Actionability

The guidance is fully concrete for an instruction-only skill: the element-by-STRIDE applicability matrix, the exact scoring formula ("score = likelihood x impact, each rated 1 (low) to 3 (high)"), the exact output path `docs/threat-models/<YYYY-MM-DD>-<feature-slug>.md`, a copy-paste-ready output template with populated example rows, and a worked example in the reference file. Per the rubric's code-vs-instruction note, the absence of code is not penalized.

Workflow Clarity

A clear five-step sequence plus a three-step from-spec workflow, with explicit checkpoints (inventory sanity rules "No magic sources or sinks", the Step 3 relevance filter, "Never fabricate threats") and an anti-patterns checklist. It falls short of the 5-anchor because there is no explicit post-write validation or re-check loop on the produced threat table (e.g., re-reviewing rows for generic mitigations before committing).

Progressive Disclosure

The ASVS anchor table and the end-to-end worked example are split into references/mitigations.md (verified to exist), referenced twice with clear context, exactly one level deep, and linking back to the SKILL.md spine. The body keeps the overview, process, and output format, matching the 5-anchor's clear overview with well-signaled one-level-deep references.

Specificity

"Walks assets and trust boundaries through Microsoft's STRIDE categories, triages threats and writes the threat model into the repo" lists several specific, third-person actions, but coverage is less granular than the comprehensive 5-anchor (only three actions, no mention of the filtering or output format steps). It exceeds the 3-anchor because more than 1-2 concrete actions are named.

Completeness

An explicit "Use when..." clause with concrete trigger conditions answers "when", and "Walks assets and trust boundaries... triages threats and writes the threat model into the repo" explicitly answers "what" including where the output lands. This matches the 5-anchor (both what and when explicit with concrete trigger phrases); the 4-anchor's weaker "when" does not apply.

Trigger Term Quality

"design, story or architecture sketch", "login, user data, payments, file uploads or an external integration", and "no threat model" are natural phrases a user would say, with synonyms for the spec artifact. A few natural variants are missing (e.g., "authentication", "PII", "API/webhook"), keeping it below the comprehensive 5-anchor.

Distinctiveness Conflict Risk

"Microsoft's STRIDE categories" combined with "about to be built with no threat model" carves a clear pre-implementation planning niche that is unlikely to fire for scanning, pentest, or code-review skills. Conflict risk is minimal, matching the 5-anchor.