But it really depends on the system your TA may use. I would contemplate just asking him once, so he can point you where to find that information in what he sends out to his customers.

For example, if I book my flights at Travel Overland (TA), I get something very different from booking directly at LH or at UA. Not every TA displays booking class information on his invoices. LH at least does is at the time of booking a flight online and when they emial you a reservation confirmation. However, you can't see it on checkmytrip.com.