The model is not the agent. The harness is. You need to read this recent study, and a blog post from @hwchase17 ... (links below). It will r…

The model is not the agent. The harness is. You need to read this recent study, and a blog post from @hwchase17 ... (links below). It will resonate deeply. This diagram from a recent paper captures something important: the architecture of a truly capable AI agent isn't about the LLM at the centre, it's about what orbits around it. Three externalisation dimensions define a harnessed agent: Memory ... Not just a context window. Working context, semantic knowledge, episodic experience and personalised memory. The agent doesn't just process, it remembers, learns and adapts. Skills ... Operational procedures, decision heuristics and normative constraints. This is how an agent knows not just what to do, but how to do it within boundaries, the encoded expertise that makes it useful in the real world. Protocols ... The connective tissue. And mediating all of this? The operational layer: sandboxing, observability, compression, evaluation, approval loops, and sub-agent orchestration. This is the shift the industry is living through right now. We spent 2022-2023 obsessing over making models smarter. Now the real engineering challenge is clear: it's building the harness infrastructure that turns a smart model into a reliable, safe, and effective agent. The LLM is the engine. The harness is the car. Study: https://arxiv.org/pdf/2604.08224 Blog: https://x.com/hwchase17/status/2042978500567609738

Source: Harrison Chase (X) | 2026-04-13

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