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!

[Siwastaja]

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?

That's called prompt injection, and it's a real safety threat wherever AIs are used. As you could guess, those who develop AIs also spend significant effort to harden them against prompt injections, but it's fluffy research and impossible to ever give guarantees. Then again - no one ever gave guarantees against traditional algorithms/software having critical bugs, and those are plenty, even though traditional software can be reasoned about and small pieces of it proven.

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

It would be interesting to see your actual, original prompt - how obvious it was that you want a 6-pin PS/2, not the 8-pin connector version.

One possible reason for failure could have been, it didn't quite get the importance of this connector aspect, and as such, maybe only looked at one of the images, but on Ebay listings it's pretty common that the first photo is representative only, and the true photo showing the important details takes extra clicks to see.

[Siwastaja]

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

Tried with Claude, your photo and "what connector, how many pins?"

Fable 5.1: "That's a 6-pin mini-DIN male plug (the PS/2 keyboard/mouse style connector)."

Opus 5.5: "This is a 6‑pin Mini‑DIN male plug, the same connector PS/2 keyboards and mice use."

Sonnet 5 (lower-tier model): "Looking at the pin layout: 6 solder pins arranged in a circle inside a round metal shield, with a molded key/notch (the small rectangular tab) to force correct orientation — that's the classic layout of a GX12/GX16-style circular aviation connector, 6-pin (sometimes just labeled "6-pin DIN-style aviation plug")."

Haiku 4.5 (lowest-tier small model): "Based on the photo, this appears to be a 7-pin or 8-pin DIN connector (circular multi-pin connector), viewed end-on."

Opus 4.6 (state of the art over 6 months ago): "That's a 5-pin DIN connector (male). Five pins arranged in a 180° semicircle with a keying notch at the top. Most commonly used for MIDI cables, though the same connector was also used for older AT keyboards and some vintage audio equipment."

Fable 5.1 and Opus 5.5 also gave good additional reasoning explaining the details correctly. Others did not.

AI fanboys are right when they say that:
* The field is moving fast
* Premium models are better than lower-cost models

In AI, nothing's guaranteed, some see success after success, others failure after failure.

[Swake]

locally running Qwen3.8:27b with xhigh reasoning gave this answer. Notice it asks a question and then provides final answer.

Code: [Select]

It's a keyed circular multi-pin DC power connector (DIN-style barrel jack) — you're looking into the socket: black plastic insulator, 6 round contacts around the perimeter, plus a larger contact/key at 9 o'clock and a plastic center key tab. So 6 signal pins + key, 7 metal contacts total.

Exact part number depends on the device — which one is this from (monitor, laptop, dock)? The pin count alone isn't a standard (it's not 3-pin Samsung, 5-pin Philips/AOC, etc.), so the device model is what pins it down.

Which device is this connector from (brand + model)? That determines the exact connector standard/part number.
Answered: a mouse

Code: [Select]

That clicks: a 6-pin Mini-DIN — the classic PS/2 mouse connector (IEC 917C / DIN 41524, "Mini-DIN 6-pin"). 6 pins around the circle + center plastic key, keyed shell. Pins: VCC, GND, clock, data, sense, ground.
AI knows a lot but has not much experience and isn't always very smart with that knowledge. It is improving, rapidly.

ps: It did not rely or took into account the name of the file (mouse--connector.png). I guess that depends on the harness.

[PlainName]

Did the agent use an Ebay API or just browse the items for sale? If the latter, perhaps it saw the wanted details in an advert for another item that Ebay runs alongside item listings?

[Doctorandus_P]

https://xkcd.com/1807/

[Kilrah]

 

[PlainName]

Is that real? I guess there is no way of actually knowing other than failing to buy stuff from the guy...

Edit: seems it is!
https://www.theguardian.com/technology/2026/sep/28/metas-ai-agent-muse-home-address

[Siwastaja]

When there are 3-4 AI giants who have been doing this AI thing for years and have established product lines, it might be a better idea to use one of them for any serious use, than an social media company's obvious toy, right after their first AI model release.

I wouldn't (and won't any time soon) let even Anthropic's or OpenAI's best models to run a shop with authority to do autonomous business decisions; and I'm sure they would do 1000x better than some Facebook joke. It seems outright crazy to use that Muse thing for anything else than entertainment purposes, which it exists for.

Play stupid games, suffer.