Really great tool, thanks!

Thank you!

In the commands, will {instance} always be rss.ponder.cat?

create account on rss.ponder cat

Or do you make the communities and then we add feeds to them?

No to all. This particular tool is only for communities on other instances. It doesn't interact with the big feeds on rss.ponder.cat.

rss.ponder.cat is for the all-RSS-post communities that I've been making. A lot of them will be pretty heavy on their posting, so some people may prefer to block the whole thing wholesale. I can add communities if people request it, but it's something I want to be a little bit careful with, so as not to create too much spam.

This new tool is designed to add RSS feeds to communities outside of ponder.cat. Something like releases of a FOSS project, weather updates for a city, things like that. The moderators of those communities can use the bot to do whatever they want within their communities, without having to involve me.

Does each message need to have only one command?

No, you can issue multiple commands. It should work fine. Of course if it gives you any issues, you can let me know.

Edit: Otter already answered, I just didn't see it. I'm leaving it for posterity, though.