Harness Engineering: The Most Important Part of AI Agents

TL;DR LLMs don’t become agents because they’re more intelligent, but because we place them inside a system that makes them usable. That system — which handles context, tools, errors, and flows — is the harness. If an agent doesn’t work, the problem is most likely not the model, but everything you’ve built around it. The agent isn’t broken. Your harness is. In recent years, we’ve seen an impressive acceleration in the world of language models. Every month (every day!) something more powerful, mor