Microsoft Updates MCP C# SDK for Stateless Requests
Version 2.0 enables stateless HTTP server transport to optimize performance in distributed AI agentic workflows.
Updated on Oct. 26, 2026 in Software
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Microsoft has released version 2.0 of its Model Context Protocol (MCP) C# SDK, which implements the July 2026 specification revision. The release introduces statelessness for HTTP servers and adds native support for Multi Round-Trip Requests to improve interactive tool performance.
Why it matters
This update optimizes MCP performance over HTTP by enabling load balancers to route traffic via standardized headers without inspecting message bodies. By moving to stateless request handling, developers can scale agentic workflows more efficiently across distributed systems.
The 2.0 release transitions Streamable HTTP servers to a default stateless configuration, managed via the HttpServerTransportOptions.Stateless property. The update removes the initialize handshake and session ID header requirements to minimize overhead.
The players
Microsoft
A global technology company that develops the .NET ecosystem, the MCP C# SDK, and various enterprise software infrastructure.
The details
The SDK now supports Multi Round-Trip Requests, which use an InputRequiredException to pause tool execution and solicit client input when necessary. To assist with enterprise security, the release implements RFC 9207 for OAuth issuer validation. Additional minor updates (versions 2.1 through 2.3) have since added subscription listeners for custom notification streams and allowed endpoint sharing across protocol revisions.
Timeline
July 28, 2026: MCP specification revision finalized.
August to October 2026: Minor SDK releases 2.1, 2.2, and 2.3 were issued.
October 26, 2026: SDK 2.0 becomes officially available.
The Tech Race
This release aligns the C# ecosystem with the latest revisions to the Model Context Protocol, a central effort to standardize how AI agents interact with external tools and data. It follows a series of updates that bridge the gap between initial protocol definitions and production-ready, stateless service architectures.
Developers can download the updated SDK packages via NuGet to begin building stateless, highly scalable agentic tools. The update requires existing .NET 8, 9, 10, or .NET Standard 2.0 environments to take advantage of the new transport modes.
The takeaway
The transition to stateless HTTP transport marks a shift toward more resilient, load-balanced AI agent architectures. Developers should monitor the project's GitHub repository for the upcoming integration of comprehensive authentication features.
What happens next
The development team is expected to focus future releases on end-to-end authentication and authorization frameworks.
Further reading
For broader trends in enterprise developer tooling, visit the Software section.
Source note: This article includes information reported by InfoQ.
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