Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 0% schema description coverage, the description compensates well: it enumerates the platform enum (ig|fb|yt), maps post_id to the correct per-platform identifier (ig_post_id / fb_post_id / yt_video_id), and offers post_uuid as an alternative. It stops short of stating that only platform is required and that exactly one of post_id/post_uuid should be supplied.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.