AI Agents: The Definitive Guide

Chapter 10. Agent Memory: How Persistence Turns Agents into Evolving Systems

At the beginning of this book, you learned that agents aren’t magic, but rather carefully engineered state machines. This will become even more obvious throughout this chapter on agent memory. Because agents don’t inherently remember anything, you need to intentionally add memory. Memory is the bridge between a clueless agent that won’t even remember your name from the beginning of a conversation, and a strategic multi-step system that knows your preferences and builds on them.

Let’s start with a simple interaction to illustrate how amnesiac agents behave without memory. I created a LangGraph agent and started a conversation where I told it my first name and that I’m writing a chapter on agent memory. This was its response:

Hi Nicole. Good luck writing your chapter on memory in AI agents.

Then, right after this, I asked it: What is my name?, to which it answered:

I don’t know your name from this chat. If you tell me what you’d like me to
call you, I’ll use it.

That might seem funny at first, but this truly shows how powerful memory is for agents. And depending on the memory type, your agent system will behave differently because memory isn’t just about how your agents use their filesystem to store and retrieve information; it’s about how they persist information across conversations and learn or forget about user preferences, instructions, or project context. This is what allows your agent system to evolve. ...