feat: implement MCP protocol version header support #404
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Add MCP-Protocol-Version header to all HTTP requests as required by MCP specification 2025-06-18. This enables proper server-side version negotiation and backwards compatibility handling. - Add protocol version constants (2025-06-18 for streamable HTTP, 2024-11-05 for SSE) - Include MCP-Protocol-Version header in all GET/POST/DELETE requests - Update WebClientStreamableHttpTransport, WebFluxSseClientTransport, HttpClientSseClientTransport, and HttpClientStreamableHttpTransport Complies with MCP specification requirement that HTTP clients MUST include protocol version header on all requests to MCP servers. Related to #398 , #363 , #250 Signed-off-by: Christian Tzolov <[email protected]>
acheshkov
approved these changes
Jul 18, 2025
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Add MCP-Protocol-Version header to all HTTP requests as required by MCP specification 2025-06-18. This enables proper server-side version negotiation and backwards compatibility handling.
Complies with MCP specification requirement that HTTP clients MUST include protocol version header on all requests to MCP servers.
Related to #398 , #363 , #250
Implementation Details:
MCP_PROTOCOL_VERSIONandMCP_PROTOCOL_VERSION_HEADER_NAMEconstants to all HTTP transport classes2025-06-18for streamable HTTP transports (WebClientStreamableHttpTransport, HttpClientStreamableHttpTransport)2024-11-05for SSE transports (WebFluxSseClientTransport, HttpClientSseClientTransport) for backwards compatibilitySpecification Reference:
This change ensures full compliance with the MCP specification requirement that "the client MUST include the MCP-Protocol-Version HTTP header on all subsequent requests to the MCP server."
Add MCP protocol version header support to all HTTP transport implementations as required by MCP specification 2025-06-18.
Motivation and Context
The MCP specification 2025-06-18 requires that HTTP clients MUST include the
MCP-Protocol-Versionheader on all requests to MCP servers. This enables:Without this header, servers cannot properly handle version-specific behavior and may not function correctly with clients using different protocol versions.
How Has This Been Tested?
Breaking Changes
No breaking changes. This is a backwards-compatible addition:
Types of changes
Checklist