How hard is it to actually build a custom tool with a working back end (not just a front end) and an MCP on top of it?

Getting a nice-looking front end built can be fast — often within 30 minutes to a weekend. But getting the back end to actually work reliably requires a real, if modest, learning curve. The suggestion is to spend time watching free YouTube tutorials or similar resources to understand the back-end steps involved (not necessarily paying for a course), including things like how to set up an OAuth connection so you don't expose your data to the outside world. The learning curve is steeper at first, but becomes much easier once you're past that initial hump.