the model alone is not the agent. The harness plus the model is the agent.

An agentic harness is the orchestration and control layer wrapped around a base language model that transforms it from a stateless text predictor into an agent capable of taking actions, calling tools, maintaining state across steps, and executing multi-step tasks. The model provides raw capability; the harness provides the structure that turns that capability into coordinated behavior. Different harnesses wrapping the same model produce materially different agent behavior, which is why harness