Tcl command to run "Tools/Generate Simulator Setup Script for IP..."?

Thank you, but that is the ip-make-simscript I mentioned above.

It would be more flexible if the information generated by the script was available in a format which is easy to parse like xml, json, tcl data structures, or similar.

For example if you are using Questa with the recent Visualizer waveform tool and dump files you will have a problem as you have to modify the msim_setup.tcl script since it uses +acc (in the elab_debug alias) and not the new -debug and -access options. But you don't want manual edits in an automated EDA flow.
If however, the information was available in xml or similar you could parse this and feed it into your own script which is using the -debug and -access options.

The old method should of course be kept (it could even use the xml parse method internally) for backwards compatibility with those who are using msim_setup.tcl.