What MCP Is: How AI Agents Connect to Real Systems

Part 2 of 6 — MCP Article Series ← Part 1: Why Connecting AI to Real Systems Is Still Hard The Model Context Protocol — MCP — is an open standard that defines how AI agents communicate with external systems. Not a library, not a framework, not a vendor product. A protocol — the same way HTTP defines how browsers and servers communicate. The practical result: write the integration once, and Any compliant Host can use it. MCP standardizes how capabilities are exposed to AI agents. It does not replace the application logic, policy checks, or orchestration that decide when those capabilities should be used and how they should be governed in production. That distinction is easy to miss in demos and hard to ignore once you ship. The difference in practice Without MCP: a developer builds a custom connector for each AI-to-system pair — OAuth2, error handling, response parsing — from scratch. That code works for one AI only. With MCP: the system exposes itself as an MCP Server. Any compliant Ho