How do I include the field description for adding fields?

Question

I would like to programmatically add fields to an existing table and include data types and field descriptions. I can add a fields with a data types with code: ALTER TABLE my_existing_table ADD COLUMN my_new_field Char(10);

Using object browser, I do not find a field Description property. Just for reference, the field description is displayed in Design View and I can manually change it.

How do I include the field description for adding fields?