Conciseness

The ~20-line body is lean with zero padding: no explanation of what a kanban board is, no library discussion, every line instructive ('One inline <style>, semantic HTML'). Every token earns its place.

Actionability

Guidance is highly concrete: a numbered workflow, an exact layout spec ('4 columns: Backlog, In progress, In review, Done... 3-6 cards per column'), and a literal output contract with the exact artifact tag. It falls short of 5 only because no sample card/column markup is shown, leaving minor interpretation room in the HTML structure.

Workflow Clarity

The sequence is clear and well-ordered (read DESIGN.md -> extract squad/sprint/columns/roster from the brief -> layout -> emit artifact per the output contract), and the operation is non-destructive so no validation cap applies. It lacks any output verification step, which keeps it at 4 rather than 5.

Progressive Disclosure

The skill is under 50 lines with no need for external references (no references/scripts/assets bundle exists), and the body is cleanly sectioned into Workflow and Output contract with no content that should be split out. The one external mention, 'the active DESIGN.md', is a workflow input, not a navigation reference.

Specificity

The description lists several concrete features — 'columns (To do / In progress / In review / Done), draggable-looking cards, assignee avatars, swimlanes, and a top filter bar' — going beyond naming the domain. It stops short of a 5 because it does not state the output medium (an HTML artifact) or any concrete actions beyond assembling the board.

Completeness

It explicitly answers both questions: the what ('Kanban / task board with columns... cards, assignee avatars, swimlanes, and a top filter bar') and the when ('Use when the brief mentions "kanban", "task board", "sprint board", "trello", "看板"') with concrete trigger phrases.

Trigger Term Quality

'kanban', 'task board', 'sprint board', 'trello', '看板' are all natural phrases a user would say, including brand and bilingual synonyms. A few plausible variants ('agile board', 'backlog board', 'work item board') are missing, so it falls just under comprehensive.

Distinctiveness Conflict Risk

It carves out a clear niche — kanban/sprint boards specifically — with triggers ('kanban', 'trello', 'sprint board') that few other skills would claim, so conflict risk is minimal. Only a very generic 'dashboard' or 'task list' skill could faintly overlap, which does not rise to the level of the anchor 4.