Detail beats the tool every time, and a Reddit post about a Tokyo trip proves it, even though the poster didn’t mean it to.
The story: the builder of a small flight and hotel booking tool for Claude says a family of 4 booked 10 nights in Tokyo and Kyoto through it. He claims the same trip would have cost $740 more on Booking.com. Then he says the tool wasn’t the reason. The prompt was. Fair warning, I can’t verify the $740, and the post is also a pitch for his own tool. Readers called that out, and they were right to. Take the number as a story and the prompt as the real material.
The Key Idea
The prompt never says “find me a cheap trip.” It tells the AI where hidden costs live, and it tells the AI how to behave when it doesn’t know something. Budget, dates, flight limits, fee rules and a final summary format are all spelled out. The model has far less room to wander, so you get comparable numbers instead of a pretty list.
Think about how a vague request plays out. “Find me a cheap Tokyo trip” gets you the lowest sticker price, and the sticker price is exactly where travel sites like to lie. A $90 a night room turns into $130 after a cleaning fee, a city tax and a “resort” charge that only shows up at checkout. A $310 flight turns into $450 once four people each add a checked bag. When the prompt names those costs ahead of time, the AI has to hunt for them instead of skipping past them. Every rule you write is one less place for a price to hide.
Three things this prompt does right
🧳 It defines what “cheap” means. It asks for the total for all 4 people, bag costs, on-time rates, airport transfers, and one option that looks cheap but isn’t once fees are added. That last request is a sneaky good one. It makes the AI show you the trap next to the deal. In practice, you might see a budget carrier at $280 per person that ends up costing more than the full-service airline once bags, seat selection and a long ground transfer from a far-off airport are counted. Seeing both side by side teaches you what to watch for on every trip after this one. Ask for the on-time rate too, because a cheap flight that gets delayed can eat a hotel night you already paid for.
📅 It gives flexibility on purpose. “I can move the dates by 2 days either way” is the line one commenter flagged as doing the heavy lifting. It turns one search into a grid of date combinations, and early January prices swing a lot. Flexibility is a lever. Hand it to the AI explicitly. A departure on a Tuesday instead of a Sunday can drop a family fare by a few hundred dollars, and you would never find that by checking one date by hand. If your dates are truly fixed, say that, and ask the AI to flex something else instead, like nearby airports or which neighborhood you stay in.
🔍 It makes the AI admit doubt and keep watching. “If you’re not sure, say so, don’t guess” cuts down on confident nonsense. “Don’t book, just search” keeps you in control. And the follow-up, checking the same flights and rooms daily until the cancellation dates, is where the savings could actually come from. Check whether your setup can really do that before you count on it. If it can’t, set a calendar reminder for yourself and paste the same prompt back in every few days. Prices drop more often than people expect, and free cancellation means you can rebook without losing anything.
How to borrow it
Swap in your own trip and keep the skeleton:
- State who is going, the dates, how far they can move, and a hard budget. Add “tell me if it’s unrealistic.”
- Ask for all-in totals with taxes, bags and fees, plus what you still pay at the hotel.
- Ask for the free cancellation date next to every price.
- Ask the AI to read recent reviews and pull out only the money problems.
- End with “start with a 5 line summary and the grand total, then the details.”
A few small tricks make this stronger. Name the fees you already know about from past trips, like resort charges or airport baggage rules, so the AI checks for them first. Tell it the format for prices, such as one currency and one total per option, so you can compare at a glance. And ask it to flag any number it couldn’t confirm, so you know which ones to verify yourself before you commit.
One honest caution. You don’t need his tool to use this. The prompt works with any assistant that can search, and you should double-check any booking before you pay. Several commenters worried about handing payment details to a third-party tool, which is a sensible instinct. Search with the AI, but book on a site you already trust.
Your move
Take your next trip, or even a weekend away, and write the fee rules before you write the destination. Then tell me what hidden cost your prompt caught. I’d love to see it! 🧭
Frequently Asked Questions
Q: Did the flexible dates do most of the work here?
One commenter thinks so. Allowing 2 days of wiggle room on each end turns one search into about 25 date combinations for flights and hotels, and early January prices can swing a lot right after New Year. Checking only the final dates on Booking.com hides that grid, so if you’re planning a similar trip, search a few date pairs before you lock anything in.
Q: Is booking directly with the hotel or airline really cheaper?
Some users insist yes and say OTAs like Booking.com are rarely the best deal. Others point out that the poster only compared against Booking.com, so the post doesn’t prove anything about direct booking. Check the hotel’s and airline’s own sites alongside the OTA for the same dates, then pick the lowest total.
Q: Is it safe to connect a booking tool like this to Claude?
One commenter suggested the tool could be spyware, while others flagged the post as undisclosed self-promotion. The post doesn’t spell out what data the tool can access, so read its permissions before you connect it. Don’t share payment details inside a chat, and finish the actual booking on the provider’s own checkout page.
This prompt saved a guy $740 on a trip to Japan
by u/Efistoffeles in PromptEngineering