Engineering Practices for Agent Harnesses
fagnerbrack · hn · 2026-07-12
This article discusses Agent Harness Engineering: how to evolve agents from merely "running" to controllable, evaluable, and iterable engineering systems.
Core focus areas include:
- Designing clear execution boundaries and tool interfaces for agents
- Logging steps, states, and failure causes via the harness for easy debugging and reproduction
- Improving stability through evaluation, replay, and constraint mechanisms rather than relying on one-off demos
- Decoupling model calls, tool calls, task orchestration, and monitoring to form a maintainable workflow
The article emphasizes that the real challenge in agent projects isn't the model itself, but the surrounding engineering, observability, and testing infrastructure.
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