AI Tech Publishing

Jan 18, 2026 · Artificial Intelligence

Understanding the AI Agent Protocol Stack: MCP, A2A, AG-UI, A2UI, AP2, and UCP

The article explains the rapidly expanding AI Agent protocol stack, clarifies that protocols form layered, non‑competing standards such as MCP, A2A, AG‑UI, A2UI, AP2 and UCP, and offers practical guidance on when and how to adopt each layer in real‑world scenarios.