Just a side note: prompts often get a disproportionate amount of attention. That is, when you copy-paste an error message into the prompt, the LLM will focus on pleasing you immediately by fixing the error message, rather than understanding and fixing the underlying issue.

A better workflow would be to let LLMs directly access the same verification tools you use. This allows LLMs to observe failures during the loop and incorporate the info more organically, without giving failures too much attention priority.

The above is based on my own experience. LLMs perform better in a positive context (e.g. constructive thinking, building outward, what to do) than in a negative one (e.g. restrictive thinking, carving context inward, what NOT to do). LLMs themselves are designed to be defensive & negative, but they get easily confused under lots of prohibitive rules. LLMs are good at expansive exploration, but suck at verification and pin-pointing what you want. (I'm not sure whether it's related, but this mantra is also true for image generation using Stable Diffusion)