I don't see the "Description" named column under Column Options via List View or Grid View. If the column is not listed under Column Options > Available Columns, then the column name does not exist as a default column name. Perhaps it is a custom column added by someone on your team. I would use Title & Step Actions columns to display any needed information in Grid View.
Custom fields can be displayed through web access but unfortunately these custom fields won’t be displayed in the MTM stand-alone Windows app.
You could submit this as a feature request to the Visual Studio product team at http://visualstudio.uservoice.com/forums/121579-visual-studio
You can post your idea there so the others can up-vote your issue.
If you submit this suggestion, you might post that link here which will benefit others who has the similar issue and can up-vote your issue so it gets more attention from the development team.
Currently, Grid View can only display:
- Test Case ID
- Test Case Title
- Test Case Step Actions
- Test Case Step Expected Result
- Test Case Reason
- Test Case State
Here's a screen shot of the grid view: