What is the adjective for "only one of many can be active at once"?

I have a toolbar in which some or all tools are in an only-one-active-at-once state. That is, if there are tools A+B+C, if A is active and I activate B, A becomes inactive.

What's the proper term for that?

The only word I can think of right now is "tabbed", but in the context I'm developing, not all tools have the visual metaphor of a tab (but some do!) which could lead to confusion.

"Modal" also came to mind, but the active state does not restrict interaction with other tools, so I don't believe it's the right word.