MCP C# SDK 2025-06-18 Update: Smart AI Features for .NET

MCP C# SDK 2025-06-18 Update: More security, interactivity & structure

With the MCP C# SDK 2025-06-18 Update .NET developers receive powerful new features for modern AI integrations. The update is based on the latest Model Context Protocol specification and brings targeted improvements to authentication, user interaction, and data structure.

Secure & standardized: New authentication

The revised authentication clearly separates the authentication server from the resource server, making it compatible with OAuth 2.0 and OpenID Connect. This improves security and facilitates integration into existing identity solutions – especially for productive AI applications.

Elicitation: Interactive user queries via schema

The new elicitation feature allows tools to request structured information from the user during execution – such as yes/no answers or input values. This makes AI experiences more context-sensitive and flexible.

For example:

On the client side, an ElicitationHandler is defined that responds to the server request.

Structured output for tools

Tools can now deliver explicitly structured results, such as lists, objects, or arrays. The SDK automatically generates an output schema based on the return type.

Conclusion

The MCP C# SDK 2025-06-18 Update is a milestone for AI applications with .NET: It brings greater security, clearly structured data flows, and a new form of interactivity. For developers, this means fewer workarounds, more standardization, and more power.