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 real value: accepted file families (spreadsheet, document, shop-floor photo), the required base64 encoding, and the 5 MB ceiling. It doesn't clarify how 'question' and 'content_base64' interact when both are supplied.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.