This script will apply the same user-entered text to the "Description" tag of each of the selected tracks.
iTunes 12 no longer provides a way to edit the Description tag of tracks in the Get Info panel for a multiple-selection of tracks.
The text you enter will be applied to the "Description" tag of the selected tracks.
Perhaps Also of Interest...
downloaded 20s ago
Apply selected CD's CD Text to its disc and track tags
downloaded 6m 0s ago
Correct song titles listed as "Artist - Song Name"
downloaded 42m 43s ago
Gather audio tracks whose files contain no artwork metadata
downloaded 44m 18s ago
Restore each selected track's artwork from an image file stored in its Album folder
downloaded 45m 45s ago
Export album artwork as folder.jpg to Album folder
downloaded 46m 0s ago
Export artwork of selected tracks to parent or specified folder