MCPNews

The Model Context Protocol ecosystem, verified

Current spec 2026-07-28

MCP header routing

transport

MCP header routing - The 2026-07-28 requirement (SEP-2243) that streamable HTTP POST requests carry standard MCP headers - Mcp-Method and Mcp-Name, alongside Mcp-Protocol-Version - so proxies and gateways can route, filter, and observe MCP traffic without parsing JSON-RPC bodies. Tool parameters can also surface as custom headers via x-mcp-header.

Header routing moves the information an intermediary needs out of the JSON-RPC body and into HTTP headers. A 2026-07-28 streamable HTTP POST must carry Mcp-Method (the JSON-RPC method) and, for named methods, Mcp-Name (the specific tool, prompt, or resource), and requests carry Mcp-Protocol-Version. Load balancers, gateways, and security tooling can route or police MCP traffic without body inspection; tool parameters can additionally surface as custom headers via x-mcp-header arguments. Enterprise gateways have started to build on exactly this surface, and it is also what makes per-method cache and policy decisions possible at the edge.

Related concepts

Sources and verification

Last verified · confidence 1.00.

  1. Official 2026-07-28 changelog - "Require standard MCP request headers (Mcp-Method, Mcp-Name) on Streamable HTTP POST requests, and add support for custom headers from tool parameters via x-mcp-header" (SEP-2243) - accessed

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