Fantastic! CLI was one of my early internal feature request for Hook as SLC product ( Simple Lovable Complete product, as opposed to MVP.). How fitting that it should be Brett Terpstra himself who delivers the goods!
One of us here at CogSci Apps has tried your CLI and happily reports success! She notes , it return an error message when the url is invalid
error: no implicit conversion of false into String
I am looking forward to trying it too.
I will reply to the hook://email URL topic