Layer 3 · Code

Agents & Tool Use

Implement a minimal tool-calling agent loop: schema definition, dispatch, and the observe-act cycle.

12 min read110 XP

Messages list (growing conversation)

Tool registry (name -> python function)

Model call (returns text or tool_call)

Dispatcher (executes + appends result)

The components of a hand-rolled agent loop.

You will usually use a framework in production, but a minimal agent loop is short enough to write from scratch and is worth doing once so the abstraction stops feeling magical.

Go deeper: L4 Foundations