In SQL 2012, there was an issue with output string formatting that missed  parameter replacement on the message that was sent as email for performance alerts. We have addressed this fix in SQL 2012 Cumulative update #2.

You can download SQL 2012 CU2 from http://support.microsoft.com/kb/2703275/LN

Related Links:
http://support.microsoft.com/kb/2699820
http://social.msdn.microsoft.com/Forums/en-US/sqldatabaseengine/thread/fd94ac66-3869-4bb6-b3b7-66066ef889ee