Millions are already being treated by doctors using artificial intelligence to take notes and draft emails to patients. But we still don't know when AI tools are accurate or biased -- or if they even save doctors time.

PALO ALTO, Calif. -- At a recent medical checkup, the doctor showed up with artificial intelligence. I got to see AI's possibilities and problems play out in a very personal way.

"Before we start, I want to just ask you a quick question," Stanford Health Care's Christopher Sharp says, opening an app on his smartphone. "I'm using a technology that records our conversation and uses artificial intelligence to summarize and make my notes for me."