I think creating a new online account, <username>.<service>.ai for all services you want to control this way, is the way to go. Then you can expose to it only the subset of your data needed for particular action. While agents can probably be made to have some similar config based on URL filtering, I am not believing for a second they are written with good intentions in mind and without bugs.

Combining this to some other practices, like redirecting the subset of mail messages to ai controled account would offer better protection. It sure is cumbersome and reduces efficency like any type of security but that beats ai having access to my bank accounts.