Agent = Model + Harness
If you have ever called an LLM API, you already know the basic shape of it. You send some text, you get some text back, and the connection closes. That is a model. It is good at producing language, bu
Series
The Harness
A five-part build of everything that wraps a model and turns it into a working agent: the loop, subagents, sandboxes, tools and memory, and observability.
Posts in this series
One Agent Is Not Always Enough
Part two of a series on agent harnesses. If you have not read part one, it introduces the idea that an agent is a model plus the harness around it. This piece builds on that, so a quick skim first wil
Letting Agents Run, Safely
Part three of a series on agent harnesses. Part one introduced the model-plus-harness idea, and part two split work across subagents. This piece is about the layer where agents stop just talking and s
Hands, Memory, and a Job to Do
Part four of a series on agent harnesses. The earlier pieces covered the model-plus-harness idea, subagents, and sandboxes. This one is about the three things that turn a capable agent into one that e
Watching the Black Box
The final part of a series on agent harnesses. We started with the model-plus-harness idea, then built subagents, gave them a safe place to work, and wired up tools, memory, and workflows. This last p
