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_denylistandtengu_mcp_listen_server_denylist. - A negotiation match is logged and falls back to the legacy handshake.
- Both states are reported in connection telemetry as
negotiationDenylistedandlistenSuppressed.
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.
Flag reading moved
The flag server now returns ["bridge.claudeusercontent.com"] for tengu_mcp_negotiation_server_denylist, read as this account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.