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 enriches parameter meaning by explaining what the tool does with each file ('each file's text and status, its courses and exams as rows') and how the data maps to what will_my_credits_transfer expects (courses as { unitid or school, code }; exams with score). This adds value beyond the schema's property descriptions.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.