How to Build an Agent (or: The Emperor Has No Clothes)
AI Summary
A working code-editing agent in about 300 lines of Go with three tools — demonstrating that the core loop behind coding agents is genuinely simple, and the sophistication lives in the harness.
Original excerpt
Ball's demystification essay: he builds a functioning code-editing agent in roughly 300 lines of Go, using three tools (read_file, list_files, edit_file) and a plain loop that feeds tool results back to the model. That's the whole trick. The essay's subtitle says the rest.
The point is not that agents are trivial — it's that the magic isn't where people think. The model plus a loop gets you a demo; everything that makes an agent trustworthy (sandboxing, verification, context management, failure recovery) lives in the harness around that loop.
This is the most-ported essay in the genre — recreated in Python, Rust, TypeScript and more — and it pairs naturally with Böckeler's harness engineering…
Frequently asked questions
What is "How to Build an Agent (or: The Emperor Has No Clothes)" about?
A working code-editing agent in about 300 lines of Go with three tools — demonstrating that the core loop behind coding agents is genuinely simple, and the sophistication lives in the harness.
Who wrote "How to Build an Agent (or: The Emperor Has No Clothes)"?
"How to Build an Agent (or: The Emperor Has No Clothes)" was written by Thorsten Ball. It is curated in the Agentic Engineering vault on Burn 451, which covers engineering with ai coding agents.
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Content attributed to the original author (Thorsten Ball). Burn 451 curates publicly available writing as a reading index. For removal requests, contact @hawking520.