Conciseness

The body is dense and directive throughout — it assumes competence, never explains general concepts, and avoids padding (e.g., "A heading labels a topic; the body makes the argument"). It earns 4 rather than 5 because a few sections carry layered qualifications that could be tightened, such as the repeated gating language in step 5 and the multi-clause edge-case rules in step 4.

Actionability

Guidance is unusually concrete for a process skill: a default artifact path (`docs/design/<descriptive-slug>.md`), a copy-paste question format block, an exact sub-agent dispatch prompt, and a verification command (`git diff --check -- <document-path>`). It stays at 4 rather than 5 because several core directives remain directional rather than executable — "Trace the production path end to end" and "Assign one clear owner to every concern" describe outcomes without a worked example showing the expected artifact.

Workflow Clarity

Nine explicitly sequenced phases with a hard gate ("Do not write the implementation plan or draft the design until this gate is complete"), explicit feedback loops (return to step 5 on unresolved decisions and on new findings from the adversarial pass), a re-validation loop ("repeat it only when the resulting revisions materially change the proposal"), and an 8-item pre-handoff checklist. This matches the anchor of clear sequence with explicit validation steps and error-recovery loops.

Progressive Disclosure

Section structure is good and the sole external reference is clearly signaled and one level deep ("Read `DESIGN-DOC-TEMPLATE.md` from this skill directory before drafting"), but that file does not exist in the skill bundle — no references/, scripts/, or assets/ directories are present — so the primary progressive-disclosure mechanism is a broken reference. Additionally, the ~220-line body inlines substantial drafting style rules and checklists that could partially live in reference files.

Specificity

Concrete actions are explicit — "Create or update implementation-ready design proposals for Mistral Vibe under docs/design, including a bounded design-tree decision review before drafting" names the deliverable, destination, and a distinct pre-drafting activity. It stays at 4 rather than 5 because the action list is short (create/update/review) and details like the adversarial review or validation plan live only in the body, leaving minor coverage gaps.

Completeness

Both halves are explicitly answered: the "what" is "Create or update implementation-ready design proposals for Mistral Vibe under docs/design" and the "when" is the concrete "Use before implementing a substantial Vibe feature, migration, protocol or API change..." clause listing specific trigger situations. This matches the anchor for clearly and explicitly answering both with concrete trigger phrases.

Trigger Term Quality

The trigger clause uses naturally spoken terms — "substantial Vibe feature, migration, protocol or API change, runtime or persistence change, cross-component workflow, compatibility plan" — which users would plausibly say. It falls short of 5 because phrases like "failure semantics" and "bounded design-tree decision review" are internal jargon rather than user vocabulary, and common phrasings like "design doc" or "write a proposal" are absent from the trigger.

Distinctiveness Conflict Risk

The description carves a clear niche (implementation-ready design proposals for Mistral Vibe) with triggers tied to pre-implementation review, so it is mostly distinct. It is not a 5 because a closely related sibling skill (`write-vibe-adr`) exists — the body explicitly disambiguates against it — but the description itself never mentions ADRs, leaving minor overlap risk when a user asks for an architecture decision record.