Letting an agent make purchases for you means...

[DiTBho]

With so much hype around AI and AI agents, I ran an experiment ...

I was looking for a specific trackball on eBay, which comes in four different interface types:

• Microsoft-style protocol over serial RS232
• SUN serial kb/mouse protocol over serial RS232
• PS/2
• USB

Since I don't have time to constantly monitor eBay
—and because I don't think eBay's "notify me" feature works well
(too many false positives and false negatives)—
I programmed and asked an AI-agent to search for it and set specific criteria for the purchase:

• brand-new condition
• price under £60, including shipping and customs
• if from abroad, shipping only via the eBay International Shipping program
• PS/2 interface

And... the agent bought a SUN serial mouse for 50 euro, from the US

!!!Experiment FAILED!

When I manually checked the listing, there was no text description and no mention of the interface type anywhere.
Though there were photos of the connector showing 8 pins.

A PS/2 connector has 6 pins.

How the hell does an agent make mistakes like this?

Stupid "stochastic parrot", can't you count, umm? Don't you know that "8 pins" is not "6 pins"? 

I gave the agent my consent to use Wikipedia online!
And, according to the logs, the agent actually consulted Wikipedia!
Where the physical PS/2 connector is clearly described!
Just like the SUN-serial one.

Moral of the story: AGI-WHAT?!?
Never trust AI; never hand over control of your wallet to it 

[DiTBho]

I really hope eBay *doesn't* implement the feature I built for fun.
Because the existing function—"notify me via email when an item matching my filter appears"—already works... terribly.

Just imagine an agent that actually "acts", making purchases on your behalf.

We already have "let eBay-AI make the auction description for you", which is prone to several errors.
But I fear that this "let agents act" will be the future of shopping on eBay and similar platforms... in the not-too-distant future.

[TERRA Operative]

The real mistake was letting the AI proceed with the purchase without you checking first....

Why did you think your experiment would even work?

[Psi]

What AI agent did you use?

[DiTBho]

What AI agent did you use?

Meta's Muse and Google’s Gemini.
An image was passed to Gemini, which was unable to recognize the PS/2 connector.

[DiTBho]

The real mistake was letting the AI proceed with the purchase without you checking first....

The experiment was prompted (by my scientific curiosity) by eBay’s new Terms of Use, which state that the platform’s updated rules prohibit scrapers, bots, and LLM-based third-party purchasing tools from placing orders without direct human oversight—unless expressly authorized through official partnerships. In my case, I obtained such authorization specifically to conduct this experiment, given that the checkout procedures remained under strict human control.

In short: I neither confirmed the order nor made the payment; I simply stopped the experiment at that point.

Why did you think your experiment would even work?

Good question ... well, given all the buzz surrounding the new rules eBay introduced for the launch of its "eBay shopping agent" — combined with the hype around OpenAI solving one of the millennium's mathematical problems (cases (C) and (D) of the Navier-Stokes equations) — I expected the restrictions to stem from the technology being mature enough to pose a genuine risk, particularly regarding speculation...

Yet it turns out it doesn't even work reliably ... 

[Obin]

One of the issues is that there is no standardization for ebay listings, so if the description is missing you're indeed relying on a language model to interpret images.
Unless you are looking for a very specific thing with a specific productcode, this kind of things are not to be dealt with by an agent. It's like asking a 5-year old the same question, you can't get mad when it gets it wrong. Aside from that, the fact that it only got it wrong based on pin-count in an image is actually amazing.

Reminds me of this image i came across recently:

source https://karthik-duraisamy.blogspot.com/2026/09/navier-stokes-regularity-what-does.html

[langwadt]

if AI-agents that can buy things on their own becomes a thing, then how long before there's ebay listings specifically crafted (with AI?) to trick those AI-agents to buy and pay?

[Stray Electron]

if AI-agents that can buy things on their own becomes a thing, then how long before there's ebay listings specifically crafted (with AI?) to trick those AI-agents to buy and pay?

  If AI is allowed to buy things on it's own, then how long before someone figures out a way to trick AI into buying things (in unsuspecting peoples' names) that they don't want?  As it is, 98% of the people don't return items (and get refunded) that they were sent by mistake and/or that they didn't order. Most people just throw the item away and eat the cost.

    Using an AI purchasing agent sounds like a great opportunity for an unscrupulous company or individual to make a LOT of money!

[dcrookston]

Don't you know that "8 pins" is not "6 pins"?

It doesn't know anything, and it doesn't understand anything.  I'm sorry you got burned, but this is your fault for trusting a language model to make financial decisions on your behalf.

[nctnico]

The real mistake was letting the AI proceed with the purchase without you checking first....

Why did you think your experiment would even work?

Agreed. What if AI ordered a 5 meter pink fallus to put in your front yard?

[negativ3]

With so much hype around AI and AI agents, I ran an experiment ...

I was looking for a specific trackball on eBay, which comes in four different interface types:

• Microsoft-style protocol over serial RS232
• SUN serial kb/mouse protocol over serial RS232
• PS/2
• USB

Since I don't have time to constantly monitor eBay
—and because I don't think eBay's "notify me" feature works well
(too many false positives and false negatives)—
I programmed and asked an AI-agent to search for it and set specific criteria for the purchase:

• brand-new condition
• price under £60, including shipping and customs
• if from abroad, shipping only via the eBay International Shipping program
• PS/2 interface

And... the agent bought a SUN serial mouse for 50 euro, from the US

!!!Experiment FAILED!

When I manually checked the listing, there was no text description and no mention of the interface type anywhere.
Though there were photos of the connector showing 8 pins.

A PS/2 connector has 6 pins.

How the hell does an agent make mistakes like this?

Stupid "stochastic parrot", can't you count, umm? Don't you know that "8 pins" is not "6 pins"? 

I gave the agent my consent to use Wikipedia online!
And, according to the logs, the agent actually consulted Wikipedia!
Where the physical PS/2 connector is clearly described!
Just like the SUN-serial one.

Moral of the story: AGI-WHAT?!?
Never trust AI; never hand over control of your wallet to it 

Did you tell the agent to never guess?
I have found this explicit instruction does away with >90% of uncertainty when asking questions.
A follow up... did you guess any of this? ... narrows it even further because they do break explicit written rules of engagement to get results.

[DiTBho]

Did you tell the agent to never guess?
I have found this explicit instruction does away with >90% of uncertainty when asking questions.
A follow up... did you guess any of this? ... narrows it even further because they do break explicit written rules of engagement to get results.

Yes, I did, and it didn't just guess.

It analyzed the listing.
There were no specs in the text; only the make and model matched, but the physical protocol wasn't specified.
So, it asked Gemini to process the photos, and it specifically got it wrong by misidentifying a photo that clearly showed 8 pins instead of 6!

And that's absurd, because if I manually ask Gemini to tell me how many pins are in a photo of PS/2 (attached pic) or Sun mouse/serial connectors ...
... well, it gives the right answer 95% of the time: 6 pins in the PS/2 pic, 8 pins in the Sun-mouse serial pic
but every now and then, it spouts nonsense.

[DiTBho]

Agreed. What if AI ordered a 5 meter pink fallus to put in your front yard?

I think I would define it as a "serious bug^2"—both because it made a mistake and because it's in poor taste.

[Kilrah]

In short: I neither confirmed the order nor made the payment; I simply stopped the experiment at that point.

And... the agent bought a SUN serial mouse for 50 euro, from the US

Maybe rephrase, cause you said it did...

But yeah, my level of surprise is basically negative. The big thing about a non-deterministic thing is... that it's non-deterministic.

[DiTBho]

Maybe rephrase, cause you said it did...

The AI was "trying to buy" a 8pin mouse instead of 6pin!