Prompt Engineering Best Practices for Production LLM Apps

The System Prompt

Your system prompt sets behavior. Be specific:

• Role and expertise
• Output format
• Constraints and guardrails
• What to do when unsure

Few-Shot Examples

Show 2-3 examples of input → output. This dramatically improves consistency.

Chain-of-Thought

Add "Think step by step" for reasoning tasks. For math and logic, require showing work.

Structured Outputs

Use JSON schema or function calling instead of parsing free text.

Testing Prompts

• Build an eval dataset (50+ examples)
• Measure accuracy, not vibes
• A/B test prompt changes
• Version your prompts like code