Sign in with your email and a one-time code. Enter your email, we send a 6-digit code (it expires in 10 minutes), and your sign-in is remembered on this browser for 30 days, so you'll rarely see the sign-in screen.
Each person only sees the tools they've been granted. A superadmin manages that on the Access tile. Tool calls are enforced server-side, so the tool backends are never reachable directly from the browser.
No code? Check spam, or use "Resend code". There's an admin-password fallback under "Use the admin password instead" for emergencies. After too many wrong attempts the backend locks out briefly; wait it out rather than guessing.