diff --git a/src/calibre/customize/__init__.py b/src/calibre/customize/__init__.py
index dfead858cd..10ae198b52 100644
--- a/src/calibre/customize/__init__.py
+++ b/src/calibre/customize/__init__.py
@@ -296,7 +296,8 @@ class Plugin(object): # {{{
     def cli_main(self, args):
         '''
         This method is the main entry point for your plugins command line
-        interface. It is called when the user does: calibre-debug
+        interface. It is called when the user does: calibre-debug -r "Plugin
+        Name". Any arguments passed are present in the args variable.
         '''
         raise NotImplementedError('The %s plugin has no command line interface'
                                   %self.name)