Why we use written contracts everywhere, but not doing it for the most important thing? Wouldn't it be wise to prepare a contract with all the possible questions with check marks or empty fields to fill for the candidate. It would be hard to answer them all, but if you want to become a president you should be very educated and have knowledge in range of topics(history, sociology, foreign policy, economics, etc). The questions whould ideally include every possible decision that a president should make in his term. If an elected president breaks the contract, he will be legitimately impeached or sued and arrested if needed. This way there would be no fools and demagogues. Now we just naively believe their beatiful words and they almost never do as they promised.
Also it would be wise to test candidates if they capable for empathy. I'm sure psychiatrists can do it. Current test for empathy(in US) I guess, not sure, it's Bible oath, which is naive.
Edit: This question although similar, not exactly a duplicate. Duplicate is when everything matches. The other question asks for legitimacy and financial liability of such an agreement, this question proposes such an agreement with it's specific set of features. Also consider agc's explanation in a comment section.