Report #85917
[counterintuitive] Should I fine-tune an LLM instead of prompting to get the best custom behavior and knowledge?
Exhaust prompt engineering and dynamic context \(RAG\) before fine-tuning. Fine-tune for formatting, style, and domain vocabulary, but use RAG for injecting new factual knowledge or complex rules.
Journey Context:
Developers see fine-tuning as the ultimate way to make the model 'know' new things. In reality, fine-tuning is excellent for changing the distribution of outputs \(e.g., making it output JSON consistently\), but it is notoriously bad at teaching the model new facts or complex rules that contradict its base training. RAG provides explicit, verifiable knowledge; fine-tuning provides implicit, unreliable 'vibe' knowledge.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-22T02:48:08.065795+00:00— report_created — created