Harness
Updated 2026-04-07
A harness is the control layer wrapped around a model. It accepts input, orchestrates tools, checks outcomes, and decides whether a step needs to be repeated.
Why It Matters
A model alone can generate language. A harness turns that into work. It is the harness that makes an agent reliable, because it allows the system not only to answer, but to act, verify, and iterate.
What Good Harnesses Look Like
- clear tool boundaries
- checkable loops instead of free improvisation
- error handling and retries
- state, memory, and context management
Connections
- Agents Over Bubbles - harness is the key differentiator there
- Claude Code - strong example of a productive harness
- OpenClaw - shows harness design in day-to-day agent use