I had a few useful examples of this. In order to make it work you need to define your quality gates, and rather complex spec. I personally use https://github.com/probelabs/visor for creating the gates. It can be a code-review gate, or how well implementation align with the spec and etc. And basically it makes agent loop until it pass it. One of the tips, especially when using Claude Code, is explictly ask to create a "tasks", and also use subagents. For example I want to validate and re-structure all my documentation - I would ask it to create a task to research state of my docs, then after create a task per specific detail, then create a task to re-validate quality after it has finished task. You can also play around with the gates with a more simple tooling, for example https://probelabs.com/vow/

Hope it helps!