Claude and an mcp and skill is plain to me. Writing your own agent connecting to LLMs to try to be better than Claude code, using Ralph loops and so on is the rabbit hole.
Though, you get such a huge bang from customizing your config that I can easily see how you could go down that slippery slope.
(I'm genuinely asking)
To give you a small taste: you need to issue an electronic invoice for each unique customer, and submit on the fly the tax authority - but these need to correlated monthly with the money in your business bank account. The paid invoices don't just go into your bank account, they are disbursed from time to time by the payment processor, on random dates that don't sync with the accounting month, so at end of month you have to have correlate precisely what invoice is paid or not. But wait, the card processor won't just send you the money in a lump sum, it will deduct from each payment some random fee that is determined by their internal formula, then, at the end of each month, add all those deducted fees (even for payments that have not been paid to you) and issue another invoice. You also have other payment channels, each with their fees etc. So I need to balance this whole overlapping intervals mess with all sort of edge cases and manual interventions I refuse to think about again.
This is one example, but there are also issues with wages and their taxation, random tax law changes in the middle of the month etc. The accountant can of course solve all this for you, but once you go a few hundred invoices per month (if you sell relatively cheap services) you are considered a "medium" business, so instead of paying for basic accounting services less than 100€ per month (have the certified accountant look over your books and sign them, as required by law), you will need more expensive packages which definitely add up to thousands in a few months.
So I naturally felt the need to (tell Claude to) build a MCP for this accounting API, and now I ask it to do accounting tasks, and then it just does them. It's really ducking sweet.
Another thing I did was, after a particularly grueling accounting month close out, I've told Claude to extract the general tasks that we accomplished, and build a skill that does it at the end of the month, and now it's like having a junior accountant in at my disposal - it just DOES the things a professional would charge me thousands for.
So both custom project MCPs and skills are super useful in my experience.