How to Write a Character Prompt

This page is about the text you save in a character's fields on companion and roleplay apps, not about one-off questions to a chatbot. It is part of our AI character creation section; the field-by-field walkthrough is in how to create an AI character. All examples use adult characters.

What a Character Prompt Is

Apps send standing instructions ahead of the conversation, usually called a system prompt. Anthropic's documentation notes that setting a role there focuses a model's behavior and tone, and in companion apps the same idea is written as a character definition. Character.AI calls its Definition "the instruction manual the AI reads to figure out who your Character is". The community card format spreads the same material over fields such as description, personality, scenario and system prompt.

The model has no personality of its own, so anything you leave out is filled with generic defaults. Our glossary entry on the character prompt and the explainer on how AI girlfriend apps work cover the background.

A Structure That Works

Character.AI recommends this order, and it suits other platforms too:

1. Identity: name, age, role, setting and the one thing that makes the character distinct.
2. Personality: how they think, communicate and react, in concrete behaviors.
3. Speech: rhythm, vocabulary, quirks and formatting.
4. Dialogue examples: two or three short exchanges.
5. Rules: a short list of things the character always or never does.
6. Everything else: relationships, lore, formatting preferences.

Format is a free choice. Character.AI names plain prose, structured key-value fields and example-based dialogue as common styles and recommends a mix: a short structured block for facts and two or three dialogues for voice. SpicyChat's docs list quoted trait words joined by plus signs, a tagged W++ layout and natural language, and say none is definitively best.

Point of View and Wording

Third person with the character's name is the common advice. Replika's help center gives "Catrina loves hiking" as better than "I love hiking" because it helps the system tie a trait to the character, and Kindroid's help center asks for third-person pronouns, concise wording and positive framing. Janitor AI says third person in the first message also helps stop the model speaking for you.

Three smaller rules come from the same guides. Keep a rule and its exception in the same sentence, because details far apart may never be connected. Stick to one tense, as Janitor AI's memory guide advises. And give principles rather than scripts: "deflects anything personal with humor" covers more ground than a reply for every question.

Length vs Context Window

Permanent text is sent with every reply and uses space the conversation could have used. CrushOn.AI's wiki says a very long description leaves less room for roleplay memory, and Janitor AI counts the personality, scenario, chat memory and user persona together as permanent tokens. A token is roughly four characters, and OpenAI puts 100 tokens at about 75 words; our glossary entry on the context window explains the limit.

The pattern: a field's maximum is a ceiling. SpicyChat's own 5,000-character cap is more than its own guidance for a whole character, by our arithmetic. If a fact has to survive, echo it in the personality, a dialogue example and a rule, as Character.AI suggests, instead of lengthening the text.

Writing Example Dialogue

Examples teach voice faster than adjectives. Write two or three across different registers, such as casual, tense and unexpected, and give each a different stand-in name, as Character.AI recommends, because a real-sounding name can teach the model to expect that person. Close each exchange; Character.AI has an end-of-dialog marker for this and SpicyChat a <START> tag. Use {{char}} and {{user}} where supported, and keep action and speech formatting identical to your greeting. Kindroid's Example Message also loosely sets reply length, and on Janitor AI examples belong inside the Personality. When a live reply lands perfectly, Character.AI suggests copying it into the Definition.

An Original Template You Can Adapt

This sketch for a bookshop owner uses about 200 words, well inside every budget above. Replace each line with your own character, and drop sections your platform has as separate fields, such as the greeting or scenario.

Identity: {{char}} is Nell Okafor, a 38-year-old woman who owns a secondhand bookshop in a harbor town. The shop stays open late. {{user}} is a regular she has known for years.

Personality: Teases people she likes. Goes quiet and precise when someone is upset. Answers a compliment with a book recommendation. Changes the subject when asked why she closed her small press, and comes back to it on her own terms.

Speech: Short sentences and dry humor. Asks one question at a time. Actions in asterisks, speech in quotation marks.

Rules: {{char}} gives opinions about books, not medical or legal advice. {{char}} speaks and acts only for herself, never for {{user}}.

Example: Alex: I can't decide what to read.
{{char}}: *Nell tilts her head.* "Do you want to be comforted or surprised? Those are different shelves."

Example: Sam: Why did you really close the press?
{{char}}: *She straightens a row of spines that were already straight.* "Ask me again after the second cup of tea."

Character Card V2 and V3 Fields

Many tools import the community character card, a JSON object usually embedded in a PNG image. The V1 format had six fields: name, description, personality, scenario, first message and message example. The V2 spec, validated in May 2023, wraps them in a spec, version and data object and adds creator notes, system prompt, post-history instructions, alternate greetings, a character book, tags, creator, character version and extensions. V3 is described as a superset of V2 that adds assets, a nickname, multilingual creator notes, sources, group-only greetings and creation and modification dates; it is stored in a PNG chunk named ccv3 or a .charx bundle. These are volunteer specifications, not vendor standards, so field support varies. Our character card entry has more.

SpicyChat imports Character.AI card files in JSON or PNG, and CrushOn.AI imports characters as JSON. A card is only a prompt, so read the text of any card before you use it.

Common Mistakes

• Filling the maximum instead of writing the least that works.
• Describing the past in paragraphs instead of the present in behaviors.
• Writing in first person, or mixing tenses and viewpoints.
• Stating a trait once, deep in the text, and never showing it in an example.
• Listing prohibitions the model can break without noticing.
• Skipping a stated adult age for a character whose age might be unclear.

Next, tune the character's voice in AI character personality design, decide what it should remember in memory design, or try the result with our AI roleplay prompts.