Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 0%, so the description must compensate. It mentions 'two numbers' which maps to parameters a and b, but does not provide individual parameter detail. Since addition is commutative, order is irrelevant, and the description is minimally adequate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.