Agent Harness: The Third Era of Working With LLMs

If you're working with LLMs and still in "prompt engineering" mode — better prompts, longer templates, more examples — you're leaving most of the value on the table.

Frontier models (Claude Opus 4.7, GPT-5.4, etc.) can now run autonomous workflows end-to-end if you build the right harness around them. Four parts: a loop, a verifiable goal, a tool set, a secure environment.

I wrote a full breakdown — the practice, the 4 components, the most common failure modes, and why "verifiable" is the most important word in this whole discipline.

We run our own sales pipeline on this architecture. It works.

Read here: https://mindpal.space/article/agent-harness