Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3, but the description adds meaning by explaining that results are ranked by relevance to query when supplied and by popularity otherwise. It does not add much beyond the schema for city, country, limit, or food_only, but the query ranking semantics are helpful.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.