The first feature you get when you load a LilyPond file (with .ly extension) into jEdit is syntax coloring. Commands, user commands, assignments etc. colored automatically for you. The syntax definition file (lilypond.xml in the jedit/modes folder) is not part (yet) of LilyPondTool, but comes with jEdit.

You can always download the latest version of this file from the jEdit source code repository at http://jedit.svn.sourceforge.net/viewvc/jedit/jEdit/trunk/modes/lilypond.xml

When the plugin is active and a .ly file is edited, jEdit provides folding handles to fold parts of the text. Click on the small triangles on the left to fold and unfold blocks of the text.

There are standard features as well, which are provided by jEdit. For example pressing Ctrl+i will indent the selected text, Ctrl-e Ctrl-k (there are double shortcuts in jEdit) will make line comments. Ctrl-b will help you complete the word based on previous word. There are many other useful features, just look in jEdit manual.