Services and URL schemes
Every app's Services menu entries and URL addresses become steps, and apps that answer back (x-callback-url) work in both directions.
switchboard scan
reads every app on this Mac for two things apps already publish.
Services #
The entries in an app's Services menu ("New Sticky Note", "Summarize", whatever you have installed) become steps named Menu title (App). They run on the text or file you give them, on a private pasteboard, so your clipboard is untouched.
URL schemes #
An app that opens addresses like bear:// gets an Open URL step with the scheme filled in. Apps with documented x-callback-url routes (Drafts, Bear, Things, Ulysses, Shortcuts, OmniFocus, Day One, Fantastical, Overcast) get a step per route, with a form, and the ones that answer return what the app sent back, such as the new draft's id.
For any other app that speaks x-callback-url, use the Call an app and read its answer (x-callback-url) step.
Search them all #
switchboard find resize searches every built-in step, extension action, API operation, command-line tool and Service at once. "Make smaller" finds "resize". The Add step picker searches the same index.