Published: 2026-06-20
Analysis & perspective
Analysis & perspective
Agent Loops Explained: Reason–Act–Observe Cycles Instead of One-Shot Prompting
Chapters / key moments (click to jump — plays here on the page)
Nate Herk demystifies "loop engineering" — the idea that instead of prompting a coding agent yourself, you design a loop that prompts the agent. A loop is a trigger, an action, and a stop condition, built on two pillars: an objective goal and a verification method. He argues most tasks don’t need elaborate agent swarms — a single reason–act–observe loop with a good "definition of done" does most of the work.
Source video
"Finally. Agent Loops Clearly Explained." by Nate Herk — Watch on YouTube →
Key Takeaways
- A loop is three things — a trigger, an action, and a stop condition — and "loop engineering" means replacing yourself as the one who prompts the agent.
- The two pillars are the goal (as objective as possible) and verification (how the agent checks its own work and knows when to stop).
- Quality climbs with attempts; outsourcing the feedback/iteration loop to the agent gets you to 90%+ far faster than one-shotting.
- Most tasks need only a solo loop — one agent reasoning, acting, observing, repeating — not fleets of agents orchestrating each other 24/7.
- The best stop conditions are measurable ("iterate until X metric equals Y"); vague ones like "until you’re satisfied" can run for 12+ hours with little payoff.
- Examples used Claude Code’s /goal command and Matthew Berman’s open Loop Library (thumbnails scored vs. a rubric, a Three.js plane, an Abbey Road recreation) — each verified visually via screenshots.
Commands & Code Mentioned
/goal # Claude Code slash command used to kick off a self-verifying loop





