Where do I get an API token for the command-line tool?

From the developer area, under API tokens: create one there and use it to sign the tool in. A token belongs to your developer account and carries its permissions, so treat it like a password — it is shown once, it is not recoverable, and anything done with it counts as done by you.

If a token is exposed or you no longer need it, delete it on that page; a deleted token stops working immediately and you can issue a new one.