I manage my Paperback collection with Calibre.

Use the "Add from ISBN" selection on the Add Books arrow.
There is even a special place there to set the Tag(s) for books added this way. Mine reads <In Paper Library>

I suggest processing in batches of 10-15 so that you can spot and resolve Meta-date look-up failures.
Buy or borrow a 'Keyboard Wedge' configured Laser barcode scanner of the quality of a Symbol 4004

(A Keyboard wedge emulates the keyboard with the scan data. You must place the insert point just like if you were typing it.) Get a USB model unless you only have PS2 ports

availble (Converters are
slow).