If you want to use Mastodon through a command line interface or text-based user interface, there's a tool you can install which offers both called "toot":
Templates can be downloaded as separate packages (usually with more than one template) or created by the user. Text & images can also be placed manually using coordinates.
Forgot to give a name to a screen when starting it? Find the id with $ screen -list and rename it like this: $ screen -rd id_number -X sessionname new_screen_name