Build an AI Agent (From Scratch)

preface

When we started building agents, the frameworks were a blessing. LangGraph, CrewAI, AutoGen, and many others made it possible to stand up a working agent in a handful of lines. But every time we tried to go deeper, either to understand why an agent behaved the way it did or to fix a failure that surfaced in production, we ended up reading through the framework’s source code. When we were inside, we kept noticing the same thing. Beneath every framework lies the same small set of ideas: message loops, tool calls, execution contexts, memory, planning, and collaboration. The names and defaults differ, but the patterns are shared.

That realization became the seed of this book. Rather than teach any single framework, we wanted to surface ...