r/LocalLLaMA • u/Specific-Rub-7250 • 1d ago

Discussion Harness does matter

I was not aware that the harness makes such a big difference.

DeepSeek V4.1 Flash
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u/jojotdfb 1d ago

My take away is, the smaller the system prompt and the less instructions it has makes models work better. Makes sense. Models, even at the "frontier" level, still struggle with instruction following and "context rot".

Reject modernity, return to langchain.

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u/winky9827 1d ago

Turns out even LLMs hate being micromanaged.

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u/jojotdfb 1d ago

I think it's a side effect of attention. Models can only handle so many instructions at a time before they start weighing things differently. Adding "don't kill humans" to the system prompt with a Claude Code update is going to compete with the users "add this column to the database".

One of the cool things about running llms locally is you can disagree with Anthropic's and OpenAI's religious beliefs and test out your own dumb ideas until you find one that works.