"Agent harness" is a concept that really only caught on this year, but the work behind it isn’t new at all. If you were building agents last year, you were already doing it: gluing tools together, hand-tuning prompts, bolting on retries and logging, and patching each failure the morning after it woke someone up. What is new is having a name for this process. The name turns out to be surprisingly useful. It lets you treat all of that capability as one thing you design on purpose, instead of a drawer full of one-off fixes.
The model is the engine. It is where the power comes from. But nobody ships a bare engine bolted to a pallet to a customer. The chassis, brakes, dashboard, and seatbelts are what make it something you’d put your family in. The model is only the engine; it is everything that makes the product safe, reliable, and pleasant to use is the harness you build around it.
The Two Halves of a Harness
The way I think about it, everything in the harness falls into two halves. Development is what extends the model’s reach: memory across sessions, tools and MCP, retrieval, prompts, and orchestration. Operations is what keeps the thing running reliably once real users show up: observability, evaluation, guardrails, routing, monitoring for drift and cost, deployment, and scaling.
Figure 3. The two halves of a harness (Source: Image created by author).
I want to be careful here, because it’s easy to look at a lopsided diagram like this and conclude the model barely matters. That’s not at all true. The model does the genuinely hard cognitive work. A stronger model lifts everything above it. The point is subtler: An AI agent isn’t a model, it’s a product. Building a good product takes far more than wrapping a model in an API, and most of that "far more" is the harness. A lot of it will feel familiar, too, if you’ve run services before: The operations half is essentially DevOps, wearing a new hat.
references
https://www.infoq.com/articles/agent-harness-build-one/?shem=dsdf,sharefoc,agadiscoversdl,,sh/x/discover/m1/4
No comments:
Post a Comment