Agent Harness
The loop needs software that supplies context and dispatches requests.
An agent harness runs interactions between a model and its tools. It supplies context, routes action requests, returns results, and manages when execution continues or stops.
[Anthropic][Hugging Face]In practice
A model requests a file read. The harness dispatches the request and supplies the returned text to the next model call.
[Anthropic]A little deeper
The harness is execution software around the model. Its boundary varies across authors and products. [Anthropic][Hugging Face]
A common mix-up
Harness and scaffold always mean different components.
Their boundaries overlap in some usage. An evaluation harness is a separate testing context. [Hugging Face]
Helpful to know: Agent Loop · Language Model · Tool Calling