https://www.vmware.com/support/developer/converter-sdk/conv50_apireference/vim.vm.GuestInfo.ToolsStatus.html
Having a response of tools_state == toolsOld is ok in my opinion since tools functionality doesn't change drastically revision to revision.
Currently vSphere will force stop your assets if your vmware tools aren't up to date (even by one small revision). This behaviour is not optimal.
The `tools_running?` check is only used in one place, the stop command in server.rb.