Optimize an AI agent to sound human, judged by an AI detector

You can tell when an LLM wrote an email. The "I hope this email finds you well" opener, the three polite paragraphs answering a one-line question. I wanted a reply-drafting agent that didn't do that, and "don't sound like an AI" turned out to be hard to put in a prompt. Banning a few phrases is easy. The rest is judgment, and a single prompt that holds across a friendly dinner invite and a recruiter cold-email took more iterations than I'd guessed. This is not only an email problem. Some platforms down-rank content that reads as AI-generated, so teams publishing at scale have a real stake in prose that clears a detector, even when a human wrote it. The workflow here applies to any of that. So I stopped hand-tuning and let LaunchDarkly agent optimization search for the prompt. You give it a judge that scores "better," and it generates prompt variations and keeps the ones that beat the bar. For the reasoning behind the feature, read the agent optimization announcement . This tutorial is the how. If you don't have an account yet, sign up for LaunchDarkly to follow along. Two pieces do the work here. Claude ( claude-haiku-4-5-20251001 ) runs both roles: it drafts the replies, and it writes each new candidate prompt when the loop asks for one. Scoring comes from GPTZero, which isn't a language model at all but a closed AI detector. I wired it in inverted, so the score is the probability a reply reads as AI and the optimizer drives it down. I went with a detector instead of an LLM-as-a-judge for a reason: grading one model's prose by asking another model whether it sounds human is exactly the call language models are unreliable at, and a tool trained for that one question gives a number you can defend. A run is cheap. Each iteration costs around $0.002 and a few seconds, so a full run lands near a penny or two, and the loop tries variations I'd never sit down and type by hand. This tutorial runs from a saved config You bootstrap the agent, the judge, and the optimization,