Don't Build Multi-Agents

Summary

Principles of Context EngineeringWe’ll work our way up to the following principles:Share contextActions carry implicit decisionsWhy think about principles?HTML was introduced in 1993. In 2013, Facebook released React to the world. It is now 2025 and React (and its descendants) dominates the way developers build sites and apps. Why? Because React is not just a scaffold for writing code. It is a philosophy. By using React, you embrace building applications with a pattern of reactivity and modularity, which people now accept to be a standard requirement, but this was not always obvious to early web developers.In the age of LLMs and building AI Agents, it feels like we’re still playing with raw HTML & CSS and figuring out how to fit these together to make a good experience. No single approach to building agents has become the standard yet, besides some of the absolute basics.In some cases, libraries such as https://github.com/openai/swarm by OpenAI and https://github.com/microsoft/autogen by Microsoft actively push concepts which I believe to be the wrong way of building agents. Namely, using multi-agent architectures, and I’ll explain why.That said, if you’re new to agent-building, there are lots of resources on how to set up the basic scaffolding [1] [2]. But when it comes to building serious production applications, it's a different story.A Theory of Building Long-running AgentsLet’s start with reliability. When agents have to actually be reliable while running for long periods of time and maintain coherent conversations, there are certain things you must do to contain the potential for compounding errors. Otherwise, if you’re not careful, things fall apart quickly. At the core of reliability is Context Engineering.Context EngineeringIn 2025, the models out there are extremely intelligent. But even the smartest human won’t be able to do their job effectively without the context of what they’re being asked to do. “Prompt engineering” was coined as a term for the effor...