diff --git a/maven-plugin-tools-generators/src/main/java/org/apache/maven/tools/plugin/generator/PluginHelpGenerator.java b/maven-plugin-tools-generators/src/main/java/org/apache/maven/tools/plugin/generator/PluginHelpGenerator.java
index 045c058..a753f8e 100644
--- a/maven-plugin-tools-generators/src/main/java/org/apache/maven/tools/plugin/generator/PluginHelpGenerator.java
+++ b/maven-plugin-tools-generators/src/main/java/org/apache/maven/tools/plugin/generator/PluginHelpGenerator.java
@@ -50,7 +50,14 @@ import java.util.List;
 import java.util.Properties;
 
 /**
- * Generates an <code>HelpMojo</code> class.
+ * Generates an <code>HelpMojo</code> class from <code>help-class-source.vm</code> template.
+ * The generated mojo reads help content from <code>META-INF/maven/${groupId}/${artifactId}/plugin-help.xml</code> resource,
+ * which is generated by this {@link PluginDescriptorGenerator}.
+ * <p>Notice that the help mojo source needs to be generated before compilation, but when Java 5 annotations are used,
+ * plugin descriptor content is available only after compilation (detecting annotations in .class files):
+ * help mojo source can be generated with empty package (and no plugin descriptor available), then updated
+ * after compilation through {@link #rewriteHelpMojo(PluginToolsRequest)} which is called from plugin descriptor XML
+ * generation.</p>
  *
  * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
  * @version $Id$