Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds extra semantic value by giving concrete examples such as 'Portland, OR' via query, '50219', and 'bost' -> Boston with fuzzy=true, plus an example explaining that Springfields are ranked by importance. This goes beyond the schema's parameter descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.