Currently, all custom item commands always send a message back to the command sender. This is great for manual commands, but not so much for automatic commands (commands that are executed by some kind of scheduler or script): it causes big spam. I intend to add a special command argument that silences the output, for instance /kci disableoutput give test_item. The idea is that putting disableoutput as first argument will execute the command on its right, but without sending any messages to the sender.

This will be implemented in Custom Items 10.1.