diff --git a/briar-api/src/org/briarproject/api/plugins/duplex/DuplexPluginFactory.java b/briar-api/src/org/briarproject/api/plugins/duplex/DuplexPluginFactory.java
index 7e42b5b462f602047f5ed11ef5cf96b4b169e721..9e8cf7021759764dc4125e17e7f0b7e475b507fe 100644
--- a/briar-api/src/org/briarproject/api/plugins/duplex/DuplexPluginFactory.java
+++ b/briar-api/src/org/briarproject/api/plugins/duplex/DuplexPluginFactory.java
@@ -2,9 +2,12 @@ package org.briarproject.api.plugins.duplex;
 
 import org.briarproject.api.TransportId;
 
+/** Factory for creating a plugin for a duplex transport. */
 public interface DuplexPluginFactory {
 
+	/** Returns the plugin's transport identifier. */
 	TransportId getId();
 
+	/** Creates and returns a plugin, or null if no plugin can be created. */
 	DuplexPlugin createPlugin(DuplexPluginCallback callback);
 }
diff --git a/briar-api/src/org/briarproject/api/plugins/simplex/SimplexPluginFactory.java b/briar-api/src/org/briarproject/api/plugins/simplex/SimplexPluginFactory.java
index b0c09575a6232f7c705c4fe29f84de9b54e3c149..bc5c955a52114a8ba732751b2ad8a0cf126c5586 100644
--- a/briar-api/src/org/briarproject/api/plugins/simplex/SimplexPluginFactory.java
+++ b/briar-api/src/org/briarproject/api/plugins/simplex/SimplexPluginFactory.java
@@ -2,9 +2,12 @@ package org.briarproject.api.plugins.simplex;
 
 import org.briarproject.api.TransportId;
 
+/** Factory for creating a plugin for a simplex transport. */
 public interface SimplexPluginFactory {
 
+	/** Returns the plugin's transport identifier. */
 	TransportId getId();
 
+	/** Creates and returns a plugin, or null if no plugin can be created. */
 	SimplexPlugin createPlugin(SimplexPluginCallback callback);
 }