Adding table column comment requires to open Alter Table window taking more steps than necessary. In Toad for Oracle an icon on the Columns tab is available to add comments without having to open Alter Table window.
Toad for SQL Server 5.7 is scheduled to include an icon named "Edit MS Description Value" in Columns tab of tables. The current release of Toad can is available via:
The current 5.7 Beta release has this icon available and can be downloaded from: http://www.toadworld.com/