Protect an MCP Server with an Authorization Server
This article explains how to secure a Model Context Protocol (MCP) server by integrating it with an authorization server, detailing the use of OAuth2 and access tokens to authenticate and authorize requests between AI models and back-end data sources.
Background
- **MCP (Model Context Protocol)** is an open protocol from Anthropic that lets AI models (like Claude) securely access external tools, databases, or APIs — essentially giving LLMs "read/write" permissions to real systems.
- **Authorization server** (e.g., OAuth 2.0 / OpenID Connect) is the standard way web apps handle login and permissions — deciding who gets access to what. The article argues this same infrastructure should govern MCP connections.
- The core problem: MCP currently lacks built-in, granular, user-specific access controls. Without an authorization server, an MCP server often gives an AI model either full access or nothing — a security risk when the AI acts on behalf of different users with different permissions.
- FusionAuth is a commercial customer-identity and access-management platform. The article presents its own product as the solution for adding OAuth-based authorization to MCP servers.