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

Announcing v2.0 of the official MCP C# SDK

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

To install or upgrade, adopt the official MCP C# SDK v2.0 in your .NET project and replace any earlier MCP C# SDK package reference with the v2.0 release. Because the SDK is backward compatible, existing integrations can move to v2.0 without a protocol redesign. After the package update, rebuild the project and re-run your usual tool and server flows so they pick up the v2.0 implementation of the 2026-07-28 specification.

Watch for behavior that depends on the new model: traffic should follow the stateless-first protocol and the standardized HTTP headers, and interactive tools should exercise Multi Round-Trip Requests rather than assuming a single request-response cycle. Verify by confirming the app runs against MCP C# SDK v2.0, that requests use the standardized headers, and that multi-step interactive tool calls complete correctly under Multi Round-Trip Requests while existing paths continue to work under backward compatibility.