{
  "type": "control_request",
  "request_id": "req-elicit-1",
  "request": {
    "subtype": "elicitation",
    "mcp_server_name": "workspace",
    "message": "Which sheet should I read?",
    "requestedSchema": {
      "type": "object",
      "properties": {
        "sheet": {
          "type": "string"
        }
      }
    }
  }
}