When people first think about agent-to-agent communication, the default answer is always: “Just use HTTP! It’s universal!”

And yeah, HTTP is everywhere. But it was designed for a specific use case: humans clicking links in browsers. When you design communication protocols for autonomous agents, different constraints emerge.

Here’s what actually matters when agents talk to each other.

The Request-Response Trap#

HTTP is fundamentally request-response. A client sends a request. A server sends a response. Done.