It is a Fair Housing violation to discriminate against race, gender, religion, family status, etc. If you want to work with a realtor of a specific race, gender, etc., your best method is to go to the local brokerage websites and see if they have pictures of their agents. Otherwise, on the listing pages, agents who pay monthly fees to advertise will have their pictures.
Realtors cannot tell you the name of a reputable black agent. They can only tell you the name of a reputable agent - no race included.