A few weeks ago I made a tool that can decompile AGN files and create a TXT file to show you which autogen is in there. I called this tool agn2txt. It is my plan to make a compiler as well for the reverse, so this would be called txt2agn. It can create an AGN file again from the TXT file with the information.
Making this tool was very useful for me to learn more about the AGN format. But I did not look at the SDK properly, since the FSX SDK also comes with a tool called AgnDump. It creates a XML file with all the information about your AGN file. So I think that instead of making a txt2agn, I might better make a xml2agn. What do you think about that?