It would be very nice if you can just type the CDS catalog code. This would allow to identify sources of interest. For example, I have a deep photo of M51and want to locate the planetary nebulae in this galaxy. First, I go to Vizier and do a search for catalogs containing PNe in M51. Then I go to PI and in the options of your script I put the catalog code that Vizier gives. The result is my image in which only the sources I'm interested on are marked.
Another important option is, IMO, to be able to select a magnitude range, with both lower and upper limits.
And another wonderful option would be to select a list of files so it annotates all of them in a single action.
Congratulations. Best regards,