The body is lean and assumes Claude's competence — it does not re-explain what a product page or variant is, and every section carries instruction rather than filler.

It gives concrete guidance (the `click[value]` action, variant examples like "1.1 pound (pack of 1)"), but the "## Action Format" section ends with "Your response must strictly follow this format:" and supplies no format, leaving the key executable detail missing.

The Core Decision Logic is a clear three-step sequence (Parse → Assess → Select) with a price-compliance check and an ambiguity feedback loop (click to see updated details before finalizing); for this simple single-action skill the workflow is unambiguous.

Content is organized into short, focused sections and defers the worked example to a real one-level reference ("as shown in the trajectory", which exists as references/trajectory.md), keeping the overview compact.

Lists multiple concrete actions — "selects a product variant (e.g., size, quantity)", "assessing the options", "selecting one that aligns with user needs", and "defaulting to a standard single unit" — rather than vague language.

Explicitly answers both what ("selects a product variant … selecting one that aligns with user needs") and when ("It is triggered when a product page displays multiple choices"), with an explicit trigger clause.

Covers natural domain terms a user would reference — "product variant", "size", "quantity", and "product detail page" — giving good coverage of how the need is expressed.

Has a clear, narrow niche — choosing among variant options on a product detail page via click[value] — with distinct triggers unlikely to fire for unrelated skills.