It takes a dozen tokens to put "when you need to do X, run `foo --help` and use it" in your CLAUDE.md.

Plenty of MCPs and plugins and whatnot out there idly consuming 5-25k tokens 24/7. How is that the same?

Because you can enable/disable MCPs and plugins just like you can choose not to include that context in CLAUDE.md .

I do it all the time. I have several MCPs configured but only enable them on demand.