Credibility with agents is earned the same way it is with any client. I have worked with people who have all kinds of letters after their name. Eventually it becomes ridiculous. A guy handed me a card a few months ago.
John Doe, CLU, ChFC, CEBS, LUTC
His letters were longer than his name.
I had to chuckle inside.
Prior boy scouts........ I used to be the same way and go after every designation I could find applicable to my previous field when I was in the military. Knowledge is more important to me than a designation.