Typing mw dock<tab> or even mw docke<tab> (where <tab> is the tab key) doesn't complete the command.

Bash completion file was created using sudo sh -c 'mw completion bash > /usr/share/bash-completion/completions/mw'. Contents of file can be provided if required.

The sub commands of mw docker (e.g. mw docker mediawiki) do tab complete. All the other top level commands also tab complete.