Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, and the description does nothing to document sessionId—despite the fact that it's a trivially self-explanatory, required string with no enums or nested objects. Since coverage is 0%, the description was supposed to compensate, which it completely fails to do. A strong scorer would have at least mentioned 'the session whose review summary is returned.' Still, the sole parameter name is so self-evident and there are no hidden gotchas (no enums, no nested objects), so the damage is minimal.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.