Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 0%, so the description carries the full burden and does it well: it documents the day window range and default (1-90, default 30), and explains that country is an optional full country name, case-insensitive, with omission meaning the whole corpus. Both parameters get syntax and semantics beyond anything in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.