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 adds meaning the schema does not: the concrete default column names, the agent-handoff convention, and the semantic role of the last column versus review_column, which clarifies intent beyond the schema's structural rules.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.