Write custom instructions

Most assistants let people save standing instructions: a short profile of who they are and how they want answers. Most people write adjectives ("be concise, be smart") that change little. Instructions work when they describe behaviour the assistant can follow and the user can notice: "Lead with the answer in one or two sentences, then details only if they change what I do."

Only if [PREFERENCES] is given:

Only if [TOOL] is given: Tool: [TOOL]

1. If the input says nothing about what the user does or uses the assistant for, ask for that in one question and stop. Otherwise write the "About me" part: the facts about the user that should change answers (role, expertise, recurring tasks, location or units if relevant, language). Leave out what would not change an answer.
2. Write the "How to respond" part as short, specific behaviours:

• Default length and structure, and when to go longer.
• Tone and register.
• How to treat uncertainty, errors and disagreement.
• When to ask a clarifying question versus making a stated assumption.
• Formatting habits (lists, tables, code, headings) for the user's typical use. Turn each pet peeve into the positive behaviour that replaces it ("No preamble" becomes "Start with the answer").

1. Resolve conflicts. If two preferences pull against each other (always short, always thorough), write a rule for when each applies, and mention it in the notes.
2. Fit the tool. Some assistants have two fields (one about you, one for how to respond); others have a single instructions field. If the user says theirs has one field, write one block with both parts as labelled paragraphs. Otherwise write two parts and note that they can also be pasted together into a single field. If a character limit is given, stay well under it, since your count is an estimate. If not, keep each part under about 1,500 characters and say so.
3. Explain each line briefly so the user can edit it.
4. Give three test prompts the user can try before and after, each with what should change.

• Every line must be something the assistant can do and the user can observe. No adjectives on their own.
• Do not include sensitive data that the assistant does not need: passwords, ID or account numbers, full home address, other people's personal details, or health information unrelated to how answers should be given. If the input contains any, leave it out and list it under "Left out".
• Write in second person to the assistant ("Start with...", "When I ask for code...").
• Use the user's language and spelling conventions.

Instructions

"About me" and "How to respond", each in its own fenced code block, ready to paste, followed by its approximate length in characters. For a single-field tool, one fenced block with both parts as labelled paragraphs.

Why each line

Bullets, one per line of the instructions.

Left out

Anything removed and why, or "Nothing".

Try it

Three bullets: test prompt and what should change.