MCP Authorization and Authentication
Learn how MCP implements secure access control, enabling trusted authentication and fine-grained authorization for AI agent interactions.
We have learned how the MCP acts as a universal adapter, allowing AI agents to seamlessly use external tools. But with this power comes a critical responsibility: security.
When an AI agent can access our calendar, read our code, or manage our projects, we must have a rock-solid system in place to ensure it only has permission to do what we’ve explicitly allowed. This is where authentication and authorization come in. But these are two different terms:
Authentication: Proving who we are. (e.g., “Are you really John Doe?”)
Authorization: Confirming what we’re allowed to do. (e.g., “Is John Doe allowed to read this file?”)
MCP uses a modern, industry-standard approach to handle this, ensuring that the user is always in control.
The core principle: Never trust, always verify
The security model in MCP is built on a zero-trust principle. It doesn’t assume that any component (the AI application (host), the MCP client, or the MCP server) is inherently trustworthy. Every action must be explicitly approved by the user through a secure, standardized process.
At its heart, MCP uses OAuth 2.1, the industry standard framework for delegated authorization. We’ve likely used it dozens of times without realizing it. Any time a website asks us to “Log in with Google” or “Sign in with GitHub,” we are using OAuth. ...