brew install imessage-ruby
This shortcut uses a Run Shell Script action commanding iMessage-ruby on macOS to send the entirety of this Gist split by each occurrence of the term "BOOKS."
The command itself:
imessage --text "Repeat Item" --contacts "Provided Input"
I left my own phone number - +15738234380 - in the Default Number field of the Ask for Input action very much on purpose - I promise it'll make my day if you use me as a test subject.