do shell script "echo $KMPARAM_ExecutingMacro" doesn't output anything.
I used the env command to output a list of environment variables (as Peter suggests here) and couldn’t find anything with the name of the executing macro, so I have to assume that information isn't available to plug-in actions.
Peter, here's a feature request: It would be great if plug-in actions were able to parse KM tokens. Failing that, it would be helpful if details of the executing macro could be passed in an environment variable.