These are some useful things to know about AmigaOS that you can use with ToolsDaemon.
I should imagine you know this already but to stop the Tools Output window from opening put >nil: ont he end of your command.
gm:gmplay [] >nil:
This is useful for opening file requesters etc for commands that don't have them.
gmplay `c:requestfile`
Uses the requestfile program to open a file requester and then sends the file you select to gmplay. the ticks are back-ticks and are generated using alt - tilde (the top left key on a UK Keyboard)
You can use this trick with any program that returns anything that could be used as a parameter for a command. There are plenty of random commands which when given a pattern return a random filename.
gm:gmplay `random gm:Midi-Files/#?`
Will play a Random Midi File.