What does Mild Cognitive Impairment (MCI) score of 21 mean? Where is this headed?

I just read a physician's note that my father's MCI score over a year ago was 21. Probably due to Parkinson's - now unable to walk or do most ADLs. He considers his "job" to be reading news online and calling his financial advisor. Since then he's made some awful financial decisions and then forgets he did them or says "I don't know what happened". (Incidents like trying to cash out a six-figure retirement to pay for minor driveway resurfacing.) How low does that score have to get before a springing POA for healthcare can be sprung? In the past he's said his attorney would be the one to contact if he were ever incapacitated. Do you just call and say, "Hi, my father seems incapacitated, can I take a look at what needs to be done to take over?"