The body is lean and assumes Claude's competence, with tight sections and no padding or explanation of known concepts; each line (parameter guard, file list, flow, follow-up mandate) earns its place.

It provides an executable call with a concrete working example ('message(action="sendAttachment", file_name="wiseflow5x.mp4")'), an explicit wrong-parameter anti-example, and a named available file, making it copy-paste ready.

The two-step process is clearly sequenced with an explicit checkpoint ('工具返回后' / after the tool returns) and an unambiguous 'no text this turn' rule; the operation is non-destructive so no validation feedback loop is required, and a simple skill can score 3 when the single action is clear.

No bundle files exist and the body references none, but the skill is under 50 lines with a single task and well-organized sections, which meets the simple-skill allowance for a top progressive-disclosure score.

It names one concrete action ('Send product demo material') but does not list multiple distinct concrete actions, matching the 'names domain and some actions, but not comprehensive' anchor rather than the multi-action score-3 example.

It states both what it does ('Send product demo material') and when to use it via an explicit 'when they ask about concrete usage, want to understand the product form, or need a first visual reference' trigger clause, satisfying the equivalent-trigger requirement that prevents the completeness cap.

Phrases like 'ask about concrete usage', 'understand the product form', and 'first visual reference' are relevant and reasonably natural, but it is a paraphrased sentence rather than a spread of common keyword variations users would say, so it falls short of good coverage.

The 'free-status customer' qualifier combined with demo-material delivery for specific pre-qualification intents forms a clear niche with distinct triggers, unlikely to collide with other skills; voice is third person.