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I think that everyone working in AI should build their own agent from scratch, at least once. Not because it's hard, but because it's surprisingly easy, which is precisely the point.

Exactly one year ago today, I read Thorsten Ball's How to Build an Agent, or: The Emperor Has No Clothes. In this blog post, which is the single piece of text that most influenced me last year, he shows how to build a fully functional coding agent from scratch in under 400 lines of code.

Shortly thereafter, we did a one-day hackathon at Ren Systems, and by the end of the day, we had our own working agent running in the terminal. We didn't even use Anthropic's Claude Code back then, so we actually typed the complete agent code manually.

Only after building our own agent did I really start to understand what agents are. I had been reading about agents for months, but something fundamentally different clicked in my brain when I saw our own agent interact with the user, interpret the intent, and iteratively choose the right tools to achieve the goal. This emergent behavior is hard to appreciate without experiencing it so directly.

Agents have become common by now, but I still recommend everyone working in this space to build one from scratch. It sounds almost esoteric, but you have to touch it yourself to really feel what's going on. The moment your agent does something you didn't explicitly program it to do is when the line between deterministic code execution and something that's conscious and thinking starts to blur. You know it's an illusion, but it's a remarkably convincing one.

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