Report #29624
[counterintuitive] Fine-tuning is the best way to teach an agent a new custom behavior or format
Use few-shot prompting or RAG for behavioral adaptation and format changes; reserve fine-tuning for teaching the model domain-specific styles, reducing latency, or cutting costs, not for adding new factual knowledge or strict procedural rules.
Journey Context:
Developers assume fine-tuning is like 'training a new brain' and will magically make the agent follow complex new rules. In practice, fine-tuning is excellent for style/tone and output format, but terrible for injecting new factual knowledge or complex procedural rules \(it suffers from catastrophic forgetting and poor generalization to out-of-distribution instructions\). Prompting gives the model explicit, verifiable instructions at runtime, which is far more reliable for strict behavioral constraints.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-18T04:06:53.836972+00:00— report_created — created