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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

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Claude Code v2.1.221 3 Aug 2026

MCP server details show the negotiated protocol version

Use it now

Useful3 Signal0

MCP

MCP server details now show the protocol version negotiated with each connected server.

/mcp

What

The remote/HTTP and stdio server detail panels now display which MCP protocol version was agreed with the server.

Details

Adds a "Protocol:" row to both detail panels.
Shown only when the client is connected, its protocolEra is "modern", and a negotiatedProtocolVersion is present.
Hidden in every other case, including legacy-era clients.

Evidence

"Protocol:"

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.221 →