I use XFire to create a webservice wrapper around my application. XFire provides the webservice interface and WSDL at runtime (or creates them at compile time, don't know exactly).
Many of our customers don't know webservices very well and additionally they simply don't read any external documentation like Javadoc. I know that it's possible to add documentation (for parameters and methods) directly to the WSDL file.
I thought about Annotations or Aegis XML files but I don't know how... Do you know a way?
Edit: I just found this JIRA issue but the last activity was 2006. Any ideas?
XFire is slowly headed for /dev/null. Use CXF instead. In other words, XFire is being deprecated in favor of CXF - it's pretty much the same developers.
Since you use the Java-first approach, I suggest you generate you WSDL once and for all with CXF's java2wsdl tool, then you put your documentation in that and tell CXF to use that documented WSDL instead of letting CXF generate its own (undocumented) WSDL at runtime/deploy-time.
This page has pretty much everything you need to know about creating a web service in CXF.