SQL Server Data Tools (SSDT) has upgraded from (Microsoft.Data.SQLClient)MDS 3.0 to MDS 5.0. MDS 5.0 has some significant benefits over MDS 3.0. It has added support to TDS 8.0, support for specifying Server SPN and Failover Server SPN on the connection etc. Please refer to this blog for more information on the benefits of the upgrade.