Prompt Engineering Foundations
Where an instruction belongs — tool description, system prompt, or user turn — why emphasis that worked on older models now causes over-triggering, and the prompt patterns that have expired.
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After this section you can
- Place an instruction in the tool description, system prompt or user turn, and say what breaks when it is misplaced
- Rewrite an emphatic, older-model prompt into plain context with reasons, structured with XML tags
- Recognise the prompt patterns that expired and name the API feature that replaced each
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Prompt Engineering Foundations
Most prompt problems are placement problems. Where an instruction lives decides whether it is followed, cached or quietly ignored, and current models follow instructions closely enough that prompts written to push older ones now overshoot.
Key idea
Put each instruction where its lifetime matches: tool descriptions for when to call a tool, the system prompt for standing rules, the user turn for this request. Then write it once, plainly, with the reason.
An instruction’s home is decided by how often it changes, not by how important it is