I’m writing this on the Shinkansen heading to Osaka, halfway through a solo 10-day trip across Japan that I planned almost entirely with AI agents. This post isn’t about how AI can write a generic itinerary — anything can do that now. It’s about the small, weirdly clever ways agents earned their keep on this trip: rewriting the itinerary in place so my own trip viewer would render the day correctly, cross-referencing Reddit, YouTube transcripts, and official sources on its own to validate each leg, optimizing a 7-hour layover down to the minute, and replanning the afternoon when check-in finished early.