Minor tidy up of cli

lib/python/qmk/cli/xap/xap.py

@@ -191,7 +191,7 @@ class XAPShell(cmd.Cmd):
 @cli.argument('-d', '--device', help='device to select - uses format <pid>:<vid>.')
 @cli.argument('-l', '--list', arg_only=True, action='store_true', help='List available devices.')
 @cli.argument('-i', '--interactive', arg_only=True, action='store_true', help='Start interactive shell.')
-@cli.argument('action', nargs='*', default=['listen'], arg_only=True)
+@cli.argument('action', nargs='*', arg_only=True, default=['listen'], help='Shell command and any arguments to run standalone')
 @cli.subcommand('Acquire debugging information from usb XAP devices.', hidden=False if cli.config.user.developer else True)
 def xap(cli):
     """Acquire debugging information from XAP devices

lib/python/qmk/cli/xap/xap_client.py

@@ -67,7 +67,7 @@ class XAPDevice:
         """Background thread to signal waiting transactions
         """
         while 1:
-            array_alpha = self.dev.read(64, 100)
+            array_alpha = self.dev.read(ResponseStruct.size, 100)
             if array_alpha:
                 token = int.from_bytes(array_alpha[:2], 'little')
                 event = self.responses.get(token)