Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
With 100% schema description coverage, all three parameters (bill, people, tip_pct) already carry descriptions and defaults in the schema. The description echoes the concepts but adds no format, ranges, or edge-case semantics, so baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.