An artificial intelligence agent harness provides the operational structure around a model. It can manage system instructions, tool schemas, permissions, memory, workspace access, approval requests, retries, output handling, and integration with terminals, editors, browsers, or external services.
A harness influences what an agent can accomplish and how safely it operates. Two agents using the same model can behave differently when their tools, context, policies, or lifecycle controls differ, so evaluations should identify the harness and configuration as well as the model.
