Thankfully, I figured out how to resolve this. As noted here:
http://googleadsdeveloper.blogspot.ca/2013/11/please-set-user-agent-or-application.html
the USER_AGENT field is an optional field. The AdWords, DFP, and DFA APIs can take a user agent string in the SOAP headers, and the client libraries all allow you to set this string in their configuration files. That said, it is in your own best interests to set this value to something unique and useful for each of your applications.