How to Build a Multi-Step AI Agent in Node.js (Without Frameworks)

How to Build a Multi-Step AI Agent in Node.js (Without Frameworks) Most "agent" tutorials reach for LangChain or AutoGPT immediately. Here's why you shouldn't — and how to build a robust, production-ready agent from scratch in 200 lines of Node.js. Frameworks like LangChain, AutoGen, and CrewAI have exploded in popularity. They promise to make building AI agents easy. And they do — right up until the moment your agent does something unexpected, and you spend three days reading 10,000 lines of framework source code to understand why. This article takes a different approach. We'll build a fully functional multi-step AI agent — capable of using tools, maintaining memory, and completing complex tasks — from scratch. No frameworks. No magic. Just Claude's API and clean Node.js. By the end, you'll understand exactly how agents work, and you'll have a solid base you can extend without fighting someone else's abstractions. What Makes an AI Agent an Agent? A simple LLM call is: user sends messa