Custom instructions

Garden · not yet reviewed Established: widely used Widely discussed since 2023-07

Standing instructions you save once, such as your role, preferred tone or formatting rules, that the AI applies to every conversation so you don't repeat yourself.

Also called: personal preferences · system prompt · profile · saved info · styles · how to respond

Connections

Understand first

Ideas this one builds on.

• Prompting (garden)

Leads on to

Ideas that build on this one.

• Compounding loop (garden)
• Custom assistants (garden)
• Onboard AI like a new hire (garden)
• Projects and knowledge (garden)
• Skills (garden)

Evolved into

Newer ideas that grew out of this one.

• Memory (garden)

Related

Often used together or easily confused.

• Sycophancy (garden)

Blueprints that practise it

• Build a style guide so AI drafts sound like you (garden)
• Hire and onboard an AI copilot for one piece of work (garden)

Resources that teach it

• Claude Cowork 101: How to automate your workday without touching code (How I AI, with JJ Englert) (garden)
• AI Style Guides: How to Help AI Write Like You (garden)
• Compound Engineering (garden)
• Compound Writing: The Ultimate Guide (garden)
• Build your personal AI copilot (garden)
• How to build your PM second brain with ChatGPT (garden)
• Assigning AI: Seven Approaches for Students, with Prompts (garden)
• Co-Intelligence: Living and Working with AI (garden)
• Wharton Generative AI Labs Prompt Library (garden)
• Instructors as Innovators: A future-focused approach to new AI learning opportunities, with prompts (garden)
• 20 Tips to Master Claude Code in 35 Minutes (Build a Real App) (garden)

Competency

• Describe the task
• Make it repeatable

Find custom instructions on the commons map ↗

You may know it from

• management a 'how to work with me' guide Some managers write a one-page user manual for new team members: how they like updates, what they care about.

In products

The same idea, under different names in different tools.

Provider	What they call it
OpenAI	ChatGPT custom instructions
Anthropic	Claude personal preferences and styles
Google	Gemini saved info

In plain words

If you find yourself typing the same things at the start of every chat (“I work at a small nonprofit”, “use plain English”, “no bullet points unless I ask”), custom instructions let you save them once. The AI reads them at the start of every conversation.

Good custom instructions are short and specific. A few lines about who you are, what you usually use AI for, and how you like answers formatted are usually enough. Long lists of rules can backfire, because the AI tries to obey all of them everywhere, even when they don’t fit.

Developers call the same idea a “system prompt”. Whatever the product calls it, it means background instructions that shape every answer.

Example

A communications officer adds: “I write for a public health department. Default to plain language at about an eighth-grade reading level. Flag any medical claim I should verify.” Every draft now arrives closer to her standard, and the flags remind her where to check.

How it connects

• It turns repeated prompting into a saved default.
• Projects scope instructions to one body of work; custom assistants and skills package them for a specific job.
• Memory later grew from the same idea, with the AI noting things itself.

Try it

Write three sentences about how you want AI to answer you, in your own words, before looking at any templates. Save them in your tool’s settings and try one ordinary request.

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Read this card as plain Markdown: /concepts/con-custom-instructions.md. Know a parallel from your own field, or a product that implements this? Add it.