If the main concern is preventing an LLM from taking some action (sending emails, text messages, adding calendar events or making phone calls), can't you just simply not allow the LLM to do that? Don't give it access.
It's not rocket science. If the LLM has no access to do those things, then it can't be tricked into doing those things.
It's not rocket science. If the LLM has no access to do those things, then it can't be tricked into doing those things.