If you’ve been building with AI recently, you’ve probably seen these terms everywhere: AI Gateway. MCP Gateway. Agent Gateway. And depending on where you read, they either sound like the same thing… or completely different systems. Which is exactly how teams end up building the wrong layer for the wrong problem. Some vendors use them interchangeably. Others define only one and ignore the rest. And if you try to piece it together yourself, you end up with a vague understanding that doesn’t really help when you’re building something real. So let’s clear this up properly. Because these three aren’t competing ideas. They sit at different layers of the same stack, and confusing them is one of the fastest ways to design the wrong architecture. The Simple Mental Model (That Makes Everything Click) Before we define anything, here’s the cleanest way to think about it: AI systems today operate across three distinct layers of traffic . Each gateway corresponds to one of them.…