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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 v2.1.234

MCP protocol negotiation can be disabled per server from remote config

Not switched on
Useful3 Signal4
MCP Notable

Remote config can force legacy MCP handshakes or suppress listening for named servers, matched by hostname.

Two remote-config hostname lists disable MCP negotiation or listening; both fall back to empty.

What

Two remote-config lists can now switch off newer MCP behaviour for named servers: one disables protocol-era negotiation, so the server gets the legacy handshake, and one suppresses listening. Servers match on URL hostname, exact or suffix, with * matching everything. Both lists fall back to empty, so nothing is disabled unless a server value says so.

Details
  • The gates are tengu_mcp_negotiation_server_denylist and tengu_mcp_listen_server_denylist.
  • A negotiation match is logged and falls back to the legacy handshake.
  • Both states are reported in connection telemetry as negotiationDenylisted and listenSuppressed.
Evidence

tengu_mcp_negotiation_server_denylist, MCP era negotiation denylist matched

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

See this entry in the whole of v2.1.234 →