diff --git a/lib/config/custom-build-vm.nix b/lib/config/custom-build-vm.nix
index 74f1504..13ec1c7 100644
--- a/lib/config/custom-build-vm.nix
+++ b/lib/config/custom-build-vm.nix
@@ -26,22 +26,26 @@ in {
       virtualisation = {
         runAsRoot = lib.mkOption {
           type = lib.types.bool;
+          description = "Whether to launch the VM as root.";
           default = false;
         };
 
         sharedHostKeys = lib.mkOption {
           type = lib.types.bool;
+          description = "Whether to share the local host SSH keys with the VM.";
           default = false;
         };
 
         virt-viewer = lib.mkOption {
           type = lib.types.bool;
+          description = "Whether to use `remote-viewer` for displaying the VM.";
           default = false;
         };
 
         qemu = {
           runInBackground = lib.mkOption {
             type = lib.types.bool;
+            description = "Whether to run the QEMU command in a background job";
             default = false;
           };
 
@@ -50,11 +54,13 @@ in {
 
             bindAddress = lib.mkOption {
               type = lib.types.str;
+              description = "The IP address for listening to incoming SPICE connections.";
               default = "127.0.0.1";
             };
 
             port = lib.mkOption {
               type = lib.types.port;
+              description = "The port for listening to incoming SPICE connections.";
               default = 5900;
             };
           };