Your computer can't take a photo of the whiteboard or tell an agent where you are. A paired phone can. An agent can ask it to take or pick a photo, share its location, read or write its clipboard, or open its share sheet with something ready to send.
Your phone asks you each time: Don't Allow, Allow Once or Always Allow. Always Allow is remembered on the phone itself, for that computer and that one ability, so nothing on the computer can give itself permission. The phone's list of computers shows what you've always allowed, with a way to reset it.
If no phone can answer, because it's off or out of reach, the agent finds out within half a minute instead of waiting, and can tell you so. Photos are scaled down and kept out of your backups.
It works the other way too. Frontier sits in your phone's share sheet, so a link, some text or a few photos from any app can go straight into a thread you pick, with a note. The thread's agents pick it up like anything else you write there.