diff --git a/uncloud/hack/vm.py b/uncloud/hack/vm.py
index e9b7719..f9cd31a 100755
--- a/uncloud/hack/vm.py
+++ b/uncloud/hack/vm.py
@@ -17,8 +17,21 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with uncloud. If not, see <http://www.gnu.org/licenses/>.
+
+# This module is directly called from the hack module, and can be used as follow:
 #
+#   Create a new VM with default CPU/Memory. The path of the image file is relative to $hackprefix.
+#   `uncloud hack --hackprefix /tmp/hackcloud --create-vm --image mysuperimage.qcow2`
 #
+#   List running VMs (returns a list of UUIDs).
+#   `uncloud hack --hackprefix /tmp/hackcloud --list-vms
+#
+#   Get VM status:
+#   `uncloud hack --hackprefix /tmp/hackcloud --get-vm-status --uuid my-vm-uuid`
+#
+#   Stop a VM:
+#   `uncloud hack --hackprefix /tmp/hackcloud --destroy-vm --uuid my-vm-uuid`
+    ``
 
 import subprocess
 import uuid