This title and article feels plucked out of my brain. Most of my work is a lot of integrations and the best way to get a room full of devs to get what is going on is via sequence diagrams. Every other method, formal or made up, is weak compared to a basic sequence diagram. You can expand from there if needs be but I find it gets people thinking in a more complete way, gets the details out and what ifs and what abouts, and then you have a nice target that teams hit with very high accuracy and completeness.

It is one of the few (only) diagram types that is easy to draw and fairly close to the real world implementation. Most other formal approaches are wonky abstractions that only true practitioners can make sense of.