Thank you for your consideration!
When creating a field, you have to specifiy a data type (e.g. Date, String, Integer...). When querying fields from mcws, knowing these field types would allow proper casting. I didn't even consider the edit type, but this would actually be useful as well in order to provide the best input field for users.
Hendrick got what I meant: Ideally I'd need an endpoint that returns the field names along with the data and edit types, or, optionally, an endpoint that I give a field name as parameter, and input and edit type are returned. Adding this data to the Library/Fields function would be ideal from my point of view, I don't know if that would break backwards compatibility though.
Edit: On the risk of sounding ungrateful, but could we maybe get relational type and allowed values as well?