Add protocol version negotiation to server initialization#223
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koic merged 1 commit intomodelcontextprotocol:mainfrom Feb 5, 2026
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Thanks for doing this!
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Thanks! Can you rebase on the latest main branch and resolve the conflicts? |
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Motivation and Context
Currently server launched enforces the latest protocol regardless of the protocols supported by the client. This leads to issues when a client (eg. Claude Desktop) supports only protocol versions (2025-06-18) behind the current version supported by the server (2025-11-25).
This PR adds full protocol version negotiation logic (as per the MCP Spec), including dropping parameters not supported by each individual protocol version, to maximize compatibility.
How Has This Been Tested?
Tested with the Chattermill MCP (proprietary).
Breaking Changes
No breaking changes expected.
Types of changes
Checklist
Additional context
A potential consideration could be to add a config option to enumerate supported protocols if the server developer wants to explicitly avoid supporting all possible protocols. Not implemented here as doesn't seem necessary.