What do you mean when you say you’re “willing to bet according to the Kelly Criterion”? If you’re proposing a bet with 99% odds and your actual belief that you’ll win the bet is also 99%, then the Kelly Criterion would advise against betting (since the EV of such a bet would be zero, i.e. merely neutral).
Perhaps you mean that the other person should come up with the odds, and then you’ll determine your bet amount using the Kelly criterion, assuming a 99% probability of winning for yourself.
But if that’s the case, he could simply mention the amount he’s willing to bet. The phrasing kinda suggested to me that he doesn’t have all the info needed to do the Kelly calculation yet.