Agent XP option enables SQL Server 2012 Agent extended stored procedures for this server. If enabled, the SQL Server Agent is available in SSMS. If not enabled, the SQL Server Agent is not available in SSMS and cannot be used to start or stop the service. This option changes to
1 when SQL Server Agent is started. This option also supports direct execution of CLR assemblies. It is not optimized to do so; it just supports this.
0 value indicates that SQL Server Agent extended stored procedures are not available (the default). A value of
1 indicates that the SQL Server Agent extended stored procedures are available.