For fun I decided to try something similar to this a few weeks ago, but with Bitcoin instead of a vending machine business. I refined a prompt instructing it to try policies like buying low, etc. I gave it a bunch of tools for accessing my Coinbase account. Rules like, can't buy or sell more than X amount in a day.

Obviously this would probably be a disaster, but I did write proper code with sanity checks and hard rules, and if a request Claude came up with was outside it's rules it would reject it and take no action. It was allowed to also simply decide to not take any actions right now.

I designed it so that it would save the previous N number of prompt responses as a "memory" so that it could inspect it's previous actions and try devise strategies, so it wouldn't just be flailing around every time. I scheduled it to run every few minutes.

Sadly, I gave up and lost all enthusiasm for it when the Coinbase API turned out to be a load of badly documented and contradictory shit that would always return zero balance when I could login to Coinbase and see that simply wasn't true. I tried a couple of client libraries, and got nowhere with it. The prospect of having to write another REST API client was too much for my current "end of year" patience.

What started as a funny weekend project idea was completely derailed by a crappy API. I would be interested to see if anyone else tried this.