Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so baseline is 3; the description earns above that by telling the agent how to fill the message field for bugs (what was done, what happened, what was expected, error text) and by imposing a content exclusion rule that no schema constraint expresses. It adds writing guidance rather than restating field names.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.