Agent performance is a harness problem too: the case for open-source harnesses plus local models
Background-Job-862 · reddit · 2026-09-12
A Reddit poster argues that a model alone doesn't determine agent performance — the harness around it matters just as much. Managed agent setups cost you control over the agent loop, context management, tool execution, retries, and state.
His thesis: real optimization needs both an open-source model and an open-source harness, giving room to experiment on:
- how the agent decides what to do next
- how much context gets passed to the model
- tool execution, retries, and stopping conditions
- state maintenance and per-task model choice
He points to Nvidia's sol-pi as an early example and predicts more optimization will shift to the harness/runtime layer rather than the model layer.
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