Currently, in server-discovery-and-monitoring.rst, we state that the default server list should be a list containing a single server at localhost:27017:

servers: a set of ServerDescription instances. Default contains one server: "localhost:27017", ServerType Unknown.

However, this does not seem to match the spec tests:

{
  "topology_description_changed_event": {
    "topologyId": "42",
    "previousDescription": {
      "topologyType": "Unknown",
      "servers": []
    },
    "newDescription": {
      "topologyType": "Single",
      "servers": [
        {
          "address": "a:27017",
          "arbiters": [],
          "hosts": [],
          "passives": [],
          "type": "Unknown"
        }
      ]
    }
  }
}

This should probably refer to the seed list, not the server list. See this discussion on #drivers for more information.

A big thanks to kevin.albertson for his help with this.