Harness
The software around a model that adds instructions, tools, permissions, and conversation state.
Illustrative conversation
- Why does the same model feel more capable in one coding assistant than another?
- Their harnesses provide different prompts, tools, permissions, context, and loop behavior.
Definition
A harness is the application layer that turns a model into a working agent. It assembles context, presents tools, routes tool calls, applies permissions, stores state, handles failures, and decides when the loop should continue or stop. The same model can behave very differently in two products because their harnesses expose different information and capabilities.
Reviewed