For what little it's worth, I'm seeing the same behavior on two Debian
boxes, each with one statically configured interface.
$ sudo nm-tool
NetworkManager Tool
State: disconnected
print_devices(): didn't get a reply from NetworkManager.
There are no available network devices.
$
$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:11:11:23:33:7E
inet addr:10.2.20.204 Bcast:10.2.255.255 Mask:255.255.0.0
inet6 addr: fe80::211:11ff:fe23:337e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:23636 errors:0 dropped:0 overruns:0 frame:0
TX packets:35086 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2042520 (1.9 MiB) TX bytes:2552131 (2.4 MiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:92 errors:0 dropped:0 overruns:0 frame:0
TX packets:92 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:6912 (6.7 KiB) TX bytes:6912 (6.7 KiB)
$
$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
allow-hotplug eth0
iface eth0 inet static
address 10.2.20.204
netmask 255.255.0.0
gateway 10.2.1.254
$
