Cannot complete the install because one or more required items could not be found.
Software being installed: Android Development Tools 16.0.1.v201112150204-238534 (com.android.ide.eclipse.adt.feature.group 16.0.1.v201112150204-238534)
Missing requirement: Android Development Tools 16.0.1.v201112150204-238534 (com.android.ide.eclipse.adt.feature.group 16.0.1.v201112150204-238534) requires 'org.eclipse.wst.sse.core 0.0.0' but it could not be found
You need to install linux-tools first. Go to Help -> Install New Software, and enter http://download.eclipse.org/technology/linuxtools/update into the Work with box. Install all of the components that appear, then restart Eclipse when prompted. Now go back to Help -> Install New Software, and enter
https://dl-ssl.google.com/android/eclipse/ into the Work with box. Go through the installation procedure again and the ADT Plugin will install successfully.