Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema has one parameter 'year' with a description 'Optional decision year to scope to'. The tool description repeats this in prose ('Optionally scoped to one decision year'). Since schema coverage is 100%, the description adds no new semantic information about the parameter, so the baseline score of 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.