Microsoft Ships MCP C# SDK 2.0 With Stateless HTTP by Default

1 reports archived1 independent sourcesupdated 11/5/2026, 15:51:36

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Microsoft released the official MCP C# SDK 2.0, implementing the 2026-07-28 MCP spec revision, the largest change since the protocol launched. The initialize handshake and Mcp-Session-Id header are gone, Streamable HTTP servers are stateless by default so any instance can serve any request without sticky routing or shared session storage, and standardized Mcp-Method/Mcp-Name headers let gateways route without parsing bodies. Multi-round-trip requests (MRTR) replace the removed server-to-client input channel during tool calls.

LATEST/Microsoft released the official MCP C# SDK 2.0, implementing the 2026-07-28 MCP spec revision, the largest change since the protocol launched. The initialize handshake and Mcp-Session-Id header are gone, Streamable HTTP servers are stateless by default so any instance can serve any request without sticky routing or shared session storage, and standardized Mcp-Method/Mcp-Name headers let gateways route without parsing bodies. Multi-round-trip requests (MRTR) replace the removed server-to-client input channel during tool calls.

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InfoQ 中文T2Nov 5, 15:51·72 pts
Microsoft Ships MCP C# SDK 2.0 With Stateless HTTP by Default
- Statelessness removes the initialize handshake and session ID; protocol version and capabilities travel with every request, so horizontal scaling needs no sticky routing
- tools/call gains Mcp-Method, Mcp-Name and Mcp-Param-* headers for gateway routing, though the body remains authoritative and mismatches return HeaderMismatch
- MRTR uses InputRequiredException plus an opaque requestState for multi-round trips, automated by McpClient when handlers are registered
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