Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3, but the description adds meaning by scoping what the query should target: the author's product-planning, MVP-scope, and AI-agent notes. This helps an agent formulate better queries than the generic 'What to look for, in words' schema text alone.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.