The information schema does cover that - and its where the comments are ultimately stored. But I have additional meta data in the system I'm building. One of the more critical pieces is the governing class for the table or field, which informs the primary model which class should be loaded to handle the table's data. Also, MySQL doesn't store relationships. It's possible to infer them through proper field naming, but they are explicitly named.
The convention I'm developing has the limitation that no field and no table can share a name arbitrarily. When the system encounters a field that has the same name as a table, it presumes the field is a foreign key for that table.
I suppose I should go back to having my own meta tables for this information.