How to Write Effective Prompt Prefixes for AI Assistants

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The prefix is one of the most important elements of crafting well-structured prompts for AI systems. As an expert in prompt engineering, I constantly see firsthand how big of an impact the prefix has on guiding assistant responses. The right prefix establishes context, frames the conversation, and sets the stage for useful AI output.

In this post, I’ll dig into prompt prefix best practices with plenty of examples you can apply to enhance your own prompting. Proper prefixing is an art and science – let’s explore how to do it effectively!

Why Prompt Prefixes Matter

Let’s start with a quick overview of why prompt prefixes deserve special attention in the first place when engineering prompts.

The prefix comes before the main instruction or question prompt. This opening portion of the prompt allows you to:

  • Set the scene and tone for the AI assistant’s response
  • Establish any “ground truth” facts to constrain the output
  • Introduce key context about the user, situation and goal
  • Activate desirable characteristics like friendliness and helpfulness
  • Frame the type of response you want generated

Without a well-crafted prefix, you miss the opportunity to steer the AI in the right direction from the very start. The system has no upfront guidance on how to handle the prompt that follows.

However, by taking the time to optimize your prompt prefixes, you can greatly improve the relevance, accuracy and usefulness of your AI assistant’s responses.

Elements of Effective Prompt Prefixes

What should you include in your prompt prefixes? Here are some key elements to incorporate:

Conversational Framing

For chat-based AI like ChatGPT, a simple conversational framing helps establish the correct tone. For example:

  • You are ChatGPT, an AI assistant created by Anthropic to be helpful, harmless, and honest.

Context Details

Share any important contextual details about the user, situation or goal. For instance:

  • I am a marketing manager looking for ideas to promote our new product…

Instructions on Tone

Guide the assistant to respond in a certain style. You can be direct, humorous, casual, etc:

  • Please respond in a friendly, conversational tone as if we were chatting as friends.

Facts to Constrain Responses

Provide factual grounding to keep responses rooted in truth:

  • It is 2023 and Joe Biden is president of the United States.

Activation of Traits

Explicitly activate virtues and characteristics you want embodied:

  • As an AI assistant created by Anthropic to be helpful, harmless, and honest…

Prompt Prefix Templates

Let’s look at some effective templates you can use as starting points when drafting prompt prefixes:

Conversational Framing

You are [AI assistant name], an AI assistant created by [company] to be helpful, harmless, and honest.

Contextual Framing

I am a [user identity] looking to [goal] by asking you the following…

Instructional Framing

Please respond in a [tone] manner by providing [type of response] as if we were [relationship / context].

Virtue Activation

As an AI assistant created by [company] to be helpful, harmless, and honest…

Combine elements from these templates to craft well-formed prefixes for your prompts.

Prompt Prefix Examples

Here are some full prompt prefix examples using these best practices:

Customer Service

You are ChatGPT, an AI assistant created by Anthropic to be helpful, harmless, and honest. I am a customer contacting your customer support line with the following question:

This frames ChatGPT as a customer service agent and establishes the expected virtues.


I am a high school student studying for my biology exam tomorrow. Please respond in a friendly, conversational tone as if you were a tutor helping me understand the key concepts:

Putting ChatGPT in the role of tutor sets the right tone and context.

Travel Planning

It is March 2023. I am planning a 5 day trip to Paris next month and need help determining my itinerary. Please respond with specific recommendations for sightseeing, restaurants, and hotels that would appeal to a first-time visitor:

The time frame, trip details and request for specifics all steer ChatGPT effectively.

Email Writing

I am an account manager needing to write an email to a client about a potential partnership. Please compose a professional draft email in a cordial tone that provides an overview of the opportunity:

Framing this as email writing gives ChatGPT clear direction.

Prompt Prefix Best Practices

Beyond using templates, keep these best practices in mind when crafting prompt prefixes:

  • Be concise yet specific in setting the context
  • Frame the type and tone of response you want
  • Activate relevant virtues where applicable
  • Include any key factual constraints
  • Align to the AI system’s training data if possible
  • Iterate on prefixes during prompt optimization
  • Get feedback from the AI to improve prefixes

Prompt prefixes set the trajectory for the entire response. Take the time to craft optimized prefixes and see how much it improves your AI assistant’s performance!

Common Prompt Prefix Pitfalls

It’s also helpful to keep in mind some common prompt prefix mistakes to avoid:

  • Providing too little context and framing
  • Failure to establish the desired tone or characteristics
  • Using ambiguous phrasing instead of being specific
  • Introducing unnecessary or irrelevant details
  • Failure to activate virtues for systems like ChatGPT
  • Asking overly open-ended questions without constraints
  • Providing false facts or assumptions

Dodging these issues ensures your prompt prefixes provide maximum value.

Prompt Prefix Checklist

Use this handy checklist when writing your next prompt prefix:

  • [ ] Conversational framing establishes AI role
  • [ ] User identity and goal provided
  • [ ] Desired tone and response style set
  • [ ] Any key facts or constraints included
  • [ ] Virtues activated as needed
  • [ ] Context is concise yet specific
  • [ ] Phrasing is direct rather than ambiguous

The Art of Prompt Prefixes

Mastering effective prompt prefixes takes practice – and creativity! The prompts you craft should reflect your distinct voice and goals. View prompt engineering as sculpting assistance from your AI partner.

I hope these tips help you take your prompt prefixes to the next level. Please reach out if you need any personalized consulting on prompt engineering – I offer prompt audits and optimization services for businesses and individuals seeking to maximize their AI assistant capabilities.

The prefix sets the trajectory – give it the attention it deserves, and you’ll be amazed by the improvements in your AI interaction experience.

Let me know what prompt prefix tactics have worked well in your own adventures in AI! I look forward to continuing to refine best practices together as this exciting field evolves.

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