ChatGPT Custom Instructions: What to Include

Custom instructions should describe how you work

The best custom instructions are not a biography. They explain your goals, preferred style, decision habits, and what kind of output helps you move forward.

Separate context from commands

Permanent instructions should include stable preferences. Temporary project details should stay in the current chat so the instruction set stays useful over time.

Use instructions as a quality system

A good instruction set tells the assistant how to handle uncertainty, when to ask questions, and how to structure answers.

Keep stable preferences separate

Stable preferences belong in custom instructions: answer length, tone, formatting, risk tolerance, and preferred decision style.

Method and references

INSPIRE & CRAFTS research paper · OpenAI prompt engineering guide · Anthropic Claude prompt engineering docs · Google Vertex AI prompt design strategies

FAQ

What should I put in ChatGPT custom instructions?

Include your goals, preferred answer style, formatting preferences, quality rules, and things the assistant should avoid.

Should custom instructions include personal details?

Only include details that improve the work. Avoid sensitive information that the assistant does not need to answer well.