Be honest, but not TOO forthcoming. If you have an anxiety disorder, it's not a good idea to put this in your cover letter or resume, or mention it in an interview. It's actually illegal for potential employers to ask you about a disability or medical condition, so you don't want to open that can of worms yourself. Instead, focus on the positive: the skills and processes you've developed to handle previous jobs, or ways of doing things that have worked best for you in your professional life. For example, if you're asked about how you handle your daily workload, you don't have to explain that you prefer emails over phone calls or stand-up meetings because you have social anxiety. You can just note that you've found it to be a more efficient and productive option in managing your day-to-day. Focus on the coping mechanisms that make you a better employee all around, not just a better employee with anxiety issues.