You can mark one MCP server in .mcp.json as the coordinator's user-facing server.
What's wrong with this entry?
MCP server config accepts an optional role field marking the server the coordinator uses to talk to the user, and the coordinator's tool filter lets that server's tools through. It is a Claude Code extension to .mcp.json, applied only on your machine, and only takes effect when coordinator mode is on via CLAUDE_CODE_COORDINATOR_MODE.
Coordinator mode is activated via the CLAUDE_CODE_COORDINATOR_MODE environment variable; this field only takes effect when coordinator mode is active.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.