Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, with each of the three optional parameters already documented in detail (lang pattern, path limitation, file_base64 formats and 25 MB cap). The description adds no parameter-specific semantics, so the baseline of 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.