One thing to keep in mind is that if we add AppStream data for command-line apps, they'll show up in Discover. I don't think it's very useful to show Kdialog in Discover, for example.

why isn't it useful? kdialog is a user facil tool. It's not like ksmserver

I dunno, it doesn't strike me as the kind of thing someone using Discover to look for apps would be interested in. Maybe I'm wrong though.

As long as Discover developers feel there needs to be a distinction between an Application installer and a package installer, kdialog doesn't belong in Discover. It doesn't even have an icon in the start menu.

It seems to me that the question here is perhaps less about command line tools and more "does this executable perform a useful function, if launched without any pre-launch input". For command line tools, that question would become "does this tool require any parameters to perform any useful function"... As a specific example, KDialog does require that, and so it seems like we'd want to not be showing that in Discover.