You need to install our server adapter.
You can either do that by using Eclipse Market place and search for JBoss Tools (Juno) **
or via the file new wizard click "additional server adapters" and find the JBoss option and install that.
Then you get the much faster and better server adapters supporting the whole suite of JBoss servers.
** we do recommend Kepler over juno because of serious performance issues in Juno.
To expand on what Max is saying:
Spring Tools Suite only includes the server tooling that comes with the eclipse bundle releases, and most of these are what we call 'stock'; basically the simplest adapters that are possible to help users get up and running in various server types.
Once we started making our own more fully-featured adapter and tooling, the eclipse wtp team stopped adding support for newer and newer versions of JBoss. So now, you need to get the tools from us, but it also forces you to get the best working and most up-to-date tools possible;)
Thanks. I did that and it is working great now.