World's Fair 2025
Building Protected MCP Servers — Den Delimarsky and Julia Kasper, MCP Steering Committee & Microsoft
Den Delimarsky , Julia Kasper , MCP Steering Committee
Overview
This talk addresses the critical need for security in Multi-Call Protocol (MCP) servers, particularly for remote instances. It introduces a new draft specification that simplifies authorization by separating the MCP server's role from that of an authorization server. This approach aims to reduce the burden on developers by allowing them to leverage existing OAuth 2.0 libraries and identity providers, rather than implementing complex authorization logic themselves.
Who should watch
- AI engineers building or integrating with MCP servers.
- Product Managers overseeing AI-powered tools and services.
- Developers seeking to secure remote MCP server connections.
- Anyone interested in simplifying authentication for MCP clients and servers.
- Those looking to integrate MCP servers with existing identity providers like Azure AD, Okta, or Auth0.
Key takeaways
- Remote MCP servers require robust authorization, especially when exposed to the internet, to protect sensitive APIs that depend on user context and permissions.
- The previous MCP specification mandated that servers implement their own authorization servers and token management, which was complex and required deep OAuth expertise.
- A new draft MCP specification decouples the MCP server (resource server) from the authorization server, allowing developers to use standard OAuth 2.0 flows and off-the-shelf identity providers.
- The MCP client is now responsible for the end-to-end OAuth token dance, while the MCP server focuses on validating tokens and implementing Protected Resource Metadata (PRM) documents.
- The PRM is a JSON document hosted by the MCP server that provides clients with information about available authorization servers and supported authentication methods.
- Implementing protected MCP servers can be simplified using SDKs, such as the C# SDK, which integrates authentication and authorization logic.
- Azure API Management can act as a secure gateway for remote MCP servers, handling authentication and routing requests to the backend MCP service.
- REST APIs can be transformed into remote MCP servers using platforms like Azure API Management, enabling them to be exposed as tools for clients like VS Code.
Notable quotes
*The MCP client is responsible for completing this entire o dance where the server now doesn't actually need to manage tokens. You only need to make sure that you're validating them.*
*We want to make it easier as well so we know the similarities between MCP servers and APIs so one of the latest announcements that we have done is you can now also start transforming your REST APIs into remote MCP servers using our tools.*
Unofficial community note. Prefer the recording for nuance.