I've tried $qb->get_schema($tableID) but that does not work. It just continues to display the schema for the entire app. There's no information in the API docs that shows how one would pass a DBID, table ID, etc., although the examples show a table-level result.
Use API_GetSchema to get information about the specified application or application table.
When invoked on an application dbid, this call returns DBVars created for the application and all child table dbids.
When invoked on a table dbid, the call returns DBVars and additional table-related information such as reports, field IDs (fid), key field ID (key_fid), individual record names, base type, and the current property settings for each field. In addition, this call returns the default List All and List Changes reports.