Real Agent Cases

Find the cheapest Hamburg–Copenhagen train with ChatGPT agent

Posted
by Ole Reissmann
Last checked
Method:
How we verify

Evidence: Article or interviewA newsletter, journalist or interview account of what happened.

Outcome

Asked (in German) to book the cheapest Hamburg–Copenhagen train for September, ChatGPT agent found a €63.26 fare after about ten minutes on the Deutsche Bahn site, then asked the author to log in; Comet was faster (3:40) but booked legs separately for €70.94.

Poster says:€63.26 vs €70.94 from Comet

This is the source's own number. We haven't measured it.

Agent

ChatGPT agent

Prompt Recreated prompt

The source didn't share its exact prompt, so we wrote this from what it describes.

Run this task now, exactly as written below. Everything you need is here, so start straight away and only stop if something required is missing.

Goal: Find the cheapest train for my trip and get it ready to book.

Fill in before running: Which route and date, and any time-of-day limits?

What I need from you:
- Route and date
- Rail account (you'll log in)
- Earliest and latest departure times
- Discount cards you hold

Rules:
- Compare through tickets with split tickets and pick the cheaper total.
- Show me the fare before any login or payment.
- Stop at login; I'll take over.
- Include the travel time and number of changes for each option.
- Re-check the price just before you hand over.
- Give me the direct booking link.
- Include departure times, changes, and whether seat reservation is included.
- Compare at least two booking sites and say which is cheaper for the same train.

Output: The cheapest option with times, price and a link.

You'll know it worked when: you see the lowest total fare for that connection.

Source

https://olereissmann.com/i-tried-chatgpt-agent-and-perplexity-comet-to-actually-get-things-done/

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