The CO-STAR Framework
Context, Objective, Style, Tone, Audience, Response
CO-STAR is one of the most complete frameworks, popularised after it won a GPT-4 prompt-engineering competition in Singapore. Its six slots force you to be explicit about the things that quietly wreck content prompts — especially Audience and Tone. It's the framework to reach for when you're producing something other people will read: marketing copy, customer emails, social posts, announcements.
Last updated · By the Prompt Orange team
Best for
Customer-facing and marketing content where tone, audience, and format need tight control.
What each part means
CO-STAR stands for Context, Objective, Style, Tone, Audience, Response. Here's what to put in each slot.
Context
The background the model needs to understand the situation.
Example: We're launching a budgeting app aimed at students.
Objective
What you want the output to achieve — the job it has to do.
Example: Get students to sign up for the free beta.
Style
The writing style or genre to follow.
Example: Punchy and conversational, like a good app-store description.
Tone
The emotional register — separate from style.
Example: Upbeat and encouraging, never preachy about money.
Audience
Exactly who the output is for. This calibrates vocabulary, references, and assumptions.
Example: UK university students who feel stressed about money.
Response
The format and structure of the answer.
Example: A 120-character app-store tagline plus three supporting bullet points.
The CO-STAR template
Copy this, fill in the brackets, and paste it into ChatGPT, Claude, Gemini, or any AI tool.
Context: [Background]. Objective: [What the output should achieve]. Style: [Writing style or genre]. Tone: [Emotional register]. Audience: [Exactly who it's for]. Response: [Format and structure of the answer].
Before & after: CO-STAR in action
See how the framework turns a vague prompt into a strong one.
“Write some marketing copy for our budgeting app.”
Too vague—AI has to guess what you want
“Context: We're launching a budgeting app for students. Objective: Drive free-beta signups. Style: Punchy and conversational, like a great app-store listing. Tone: Upbeat and encouraging, never preachy about money. Audience: UK university students who feel stressed about their finances. Response: A 120-character tagline plus three supporting bullet points, each under 15 words.”
Specific, clear, ready to use
Why this works:
CO-STAR separates Style from Tone and forces an explicit Audience and Objective — so the copy speaks to stressed students, sounds encouraging rather than lecturing, and is aimed at one measurable goal. The Response slot keeps the output in a ready-to-use shape.
Tips for getting the most from CO-STAR
Distinguish Style from Tone: Style is the genre/format of the writing; Tone is how it should feel. Naming both gives you fine control.
Be concrete in Audience — demographics plus mindset ("stressed about money") beats a vague label.
CO-STAR is heavier than you need for quick internal tasks; save it for content that will be seen by customers or a public audience.
Pair the Objective with a measurable outcome where you can — it keeps the copy purposeful.