How to Install / Upgrade: Announcing v2.0 of the official MCP C# SDK

MCP C# SDK v2.0 implements the 2026-07-28 specification. The release centers on a stateless-first protocol, standardized HTTP headers, and Multi Round-Trip Requests for interactive tools, and it stays backward compatible with existing usage.

To install or upgrade, move your project to MCP C# SDK v2.0 and pull the updated package from your usual .NET package source so the app references the v2.0 assemblies. Rebuild after the dependency change so the new protocol behavior, HTTP header handling, and Multi Round-Trip Request support are compiled in.

Because the SDK is backward compatible, most existing clients and servers should keep working after the upgrade, but retest any interactive tools that rely on multi-step exchanges and confirm that HTTP traffic uses the standardized headers. After you deploy, verify that calls complete under the stateless-first protocol and that multi round-trip tool flows still return the expected results.