What's the smallest CLAUDE.md that actually changes behavior?

Five lines that all name a command or a file do more than 300 lines of prose:

1. npm run check before saying done, paste the output.
2. grep lib/ before writing a helper.
3. Never touch tests/ unless asked.
4. One change per response.
5. Ask before adding a dependency.

Everything else goes in CONTEXT.md as a glossary. Rules the model can execute stick; rules it must remember fade.