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Protecting Your MCP Server

Learn how to secure your MCP server with OAuth 2.1 authentication.

25 min read
mcpauthenticationoauthsecuritytask-manager

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Learning Objectives

By the end of this lesson, you will:

  • Understand why authentication matters for MCP servers
  • Learn the OAuth 2.1 flow for MCP
  • See how to implement user-scoped data
  • Know the different authentication patterns

Why Authentication Matters

MCP servers often access sensitive data:

  • User documents (Notion)
  • Financial records
  • Customer information
  • Internal systems

Without authentication, anyone can call your tools. With MCP becoming the standard for AI integrations, security isn't optional.

The MCP Authorization Spec

MCP uses OAuth 2.1 for authentication. The flow:

  1. Client requests access to your server
  2. User authenticates (login, OAuth provider, etc.)
  3. Server issues a token
  4. Client includes token in all requests
  5. Server validates token before executing tools

Implementation Patterns

PatternUse Case
API KeySimple, server-to-server
OAuth 2.1User-specific access, ChatGPT Apps
JWTStateless, self-contained tokens

For ChatGPT Apps (and most production use), you'll use OAuth 2.1.

Task Manager Example

The Task Manager MCP Server demonstrates:

  • OAuth 2.1 flow with a provider (Auth0, Supabase, etc.)
  • User-scoped data (each user sees only their tasks)
  • Token validation on every tool call

The Authentication Flow

User clicks "Connect" in ChatGPT
    ↓
Redirected to your OAuth provider
    ↓
User logs in / authorizes
    ↓
Redirected back with auth code
    ↓
Your server exchanges code for token
    ↓
All future requests include token

Try It Yourself

This server requires you to sign in. Experience what authenticated MCP feels like.

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