# Instruction Placement and Repetition — Prompt & Context Engineering

Source: https://www.skillbyai.com/en/prompt-context-engineering/o-place

> Put rules where they work and restate the critical ones.

## Rules first, reminders last

Durable rules (role, policies, output format) belong in the **system instructions** at the top, where they are stable and cacheable. In long contexts, a short **reminder of the key constraints** right before or after the question (for example: answer only from the documents, reply in JSON) helps the model apply them after reading thousands of tokens. Avoid contradictory instructions spread across sections; when a rule changes, change it in one place. Keep instructions positive and specific: say what to do, with an example of the format.

## A layout that works for long contexts

Stable on top, variable below, reminder at the end.

```text
[system]    role, rules, output format (stable, cacheable)
[examples]  2-3 selected examples
[history]   summary + last few turns
[documents] <document id=...> ... </document>  (best first)
[question]  the user request
[reminder]  "Answer only from the documents; cite ids; reply in the JSON schema."
```

## One source of truth for rules

Keep rules in one versioned file and render them into the prompt; duplicated rules drift apart.

**Quiz:** Why add a short reminder near the question in long contexts?

- [ ] It replaces the system prompt
- [x] It helps the model apply key constraints after reading a lot of content
- [ ] It doubles the context window
- [ ] It removes the need for evaluation

*Answer:* It helps the model apply key constraints after reading a lot of content. A brief restatement of the critical rules is cheap and often helps.