MCP Server Authorization

LumoAuth provides first-class support for securing Model Context Protocol (MCP) servers with OAuth 2.0 authorization. Register MCP servers as protected resources, configure scopes, and let LumoAuth handle the authorization server discovery and token issuance for AI tools and agents.

MCP Authorization Specification

This implementation follows the MCP Authorization specification (draft) and implements the required standards: OAuth 2.1, RFC 9728 (Protected Resource Metadata), RFC 8707 (Resource Indicators), and RFC 8414 (Authorization Server Metadata).

What is MCP?

The Model Context Protocol (MCP) enables AI applications (MCP clients) to connect to external tools and data sources (MCP servers). When an MCP server exposes sensitive resources, it needs authorization to ensure only permitted clients and users can access it.

In the MCP authorization model, LumoAuth acts as the OAuth 2.0 Authorization Server, your MCP server acts as the Resource Server, and AI applications act as OAuth Clients.

Architecture

Key Concepts

Roles

Role	Description	In LumoAuth
Authorization Server	Issues access tokens and handles user authentication	LumoAuth serves this role
Resource Server (MCP Server)	Hosts tools, resources, and prompts; validates Bearer tokens	Your registered MCP server
Client (MCP Client)	AI application that connects to MCP servers on behalf of users	Registered as an OAuth client in LumoAuth

Standards Implemented

Standard	Purpose
OAuth 2.1	Core authorization framework with security best practices
RFC 9728	OAuth 2.0 Protected Resource Metadata - how MCP clients discover the authorization server
RFC 8707	Resource Indicators - binding tokens to specific MCP server audiences
RFC 8414	Authorization Server Metadata - discovering LumoAuth endpoints
RFC 7591	Dynamic Client Registration - MCP clients can self-register

Quick Start

To secure an MCP server with LumoAuth:

1. Register your MCP server in the LumoAuth Tenant Portal under Developer > MCP Servers
2. Configure your MCP server to return 401 Unauthorized with a WWW-Authenticate header pointing to LumoAuth's Protected Resource Metadata
3. Validate tokens using LumoAuth's token introspection endpoint and verify the audience matches your server's Resource URI

API Endpoints

GET /t/\{tenantSlug\}/api/v1/.well-known/oauth-protected-resource/mcp/\{serverId\}

Returns the OAuth 2.0 Protected Resource Metadata (RFC 9728) for a specific MCP server. View details →

GET /t/\{tenantSlug\}/api/v1/.well-known/oauth-protected-resource

Root-level Protected Resource Metadata endpoint. Returns metadata for the tenant's MCP servers. View details →

GET /t/\{tenantSlug\}/api/v1/mcp/servers

List all active MCP servers for a tenant (requires Bearer token). View details →

GET /t/\{tenantSlug\}/api/v1/mcp/servers/\{serverId\}

Get details of a specific MCP server including discovery URLs. View details →

GET POST /t/\{tenantSlug\}/api/v1/mcp/\{serverId\}/challenge

Test the 401 challenge flow for an MCP server. Returns WWW-Authenticate header for unauthenticated requests. View details →