What I believe is that the most common mistake teams make with interaction protocols is assuming that structure alone guarantees clarity. It does not. The real failure happens when protocols are rigid but lack intent modeling. Teams define message formats and response types, but they do not account for ambiguity, fallback, or interruptions. We saw this early on when building agent-to-agent interactions for test orchestration. Two agents would follow the protocol perfectly but stall when an unexpected status update or missing context appeared. To avoid this, we design every interaction protocol with a layered model. The top layer handles expected actions. The second layer catches unclear or edge cases and redirects them to a reasoning loop. This keeps the system from freezing or misfiring. Good protocols are not just predictable. They are adaptive. If you only plan for best-case interactions, your system will break the moment things get messy.
The biggest mistake? Designing the protocol for the ideal case instead of the *real* case. Teams map out clean, perfect flows where everything goes right—no delays, no ambiguity, no human weirdness. Then it hits production and breaks the second someone hesitates, interrupts, or goes off-script. To avoid this, stress-test with edge cases, awkward pauses, and messy inputs early. Build your protocol to flex, not just function. Real-world resilience beats textbook elegance every time.