Let's talk about why Cursor's agent harness is so good. There's a misconception that first-party harnesses from the labs will always outperform. For many reasons, that isn't true. There are roughly 6 layers that go into a good agent harness: orchestration, context, routing, transport, state, and execution (tools). Some of those involve careful context engineering, and others look a lot like the traditional craft of building great software. Each of these layers needs to be optimized. And if any one of them is degraded, it can severely impact your experience with the agent. This blog post is mostly focused on context and tools, and there's still so much more to talk about there. We also want to spotlight the other (very crucial!) areas soon. There's a lot more misinformation around the agent harness out there. I'll keep writing about how we build it behind the scenes.