---
id: con-custom-instructions
schema: concept/1
layer: garden
status: established
name: Custom instructions
aka: ["personal preferences", "system prompt", "profile", "saved info", "styles", "how to respond"]
summary: >
  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.
first_seen: "2023-07"
relations:
  builds_on: [con-prompting]
  evolved_from: []
  related: [con-sycophancy]
  parallels:
    - idea: "a 'how to work with me' guide"
      field: "management"
      note: "Some managers write a one-page user manual for new team members: how they like updates, what they care about."
implementations:
  - { provider: openai, name: "ChatGPT custom instructions" }
  - { provider: anthropic, name: "Claude personal preferences and styles" }
  - { provider: google, name: "Gemini saved info" }
competencies: [cmp-describe-the-task, cmp-make-it-repeatable]
origin:
  kind: ai-proposed
  by: "seed agent 2026-10-16"
  rationale: "The first step from one-off prompts toward reusable context; parent idea for projects, skills and assistants."
---

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.