Add [Table [Description

EXEC sys.sp_addextendedproperty
	@name=N'MS_Description',
	@value=N'Table description here' ,
	@level0type=N'SCHEMA',
	@level0name=N'dbo',
	@level1type=N'TABLE',
	@level1name=N'sample_table';

Add Column Description

EXEC sys.sp_addextendedproperty
	@name=N'MS_Description',
	@value=N'Column description here' ,
	@level0type=N'SCHEMA',
	@level0name=N'dbo',
	@level1type=N'TABLE',
	@level1name=N'sample_table',
	@level2type=N'COLUMN',
	@level2name=N'c1';

Drop Extended Property

EXEC sys.sp_dropextendedproperty 
	@name=N'MS_Description',
	@level0type=N'SCHEMA',
	@level0name=N'dbo', 
	@level1type=N'TABLE',
	@level1name=N'TableName';