Tessio does, of course, possess the same knowledge in the book. It could just be that Puzo wanted to give him some things to do, because he's an elusive character most of the time.
I disagree Pete. Afterall, it was Tessio who got to dance with little girls at the wedding, who was the only one to eat an orange (or at least pick up one) in the entire movie, and to pick up packages at the gate. Those are high profile and important things to do.
