Learn to Prompt LLM Tools and Prompt Engineering-5 of 10

Master prompt crafting strategies such as how to use role instructions in prompt engineering for better results. Discover practical tips and techniques to enhance your communication skills.

January 17, 2025 – Reading Time: 14 minutes

If you missed earlier lessons of this course, you can find it and all of the lessons in this series on the main Learn Prompt Engineering Basics page.

Role instructions in prompt engineering: An abstract illustration of artificial intelligence with a brain-shaped circuit board.

Day 5: Leveraging Role Instructions for More Controlled AI Responses

Artificial intelligence models often behave unpredictably if left to their own devices. They rely on prompts provided by humans, and one of the more sophisticated methods to channel these interactions is through system instructions.

These instructions, also called role instructions, set the stage for how the AI responds: its tone, style, and persona when formulating answers. By defining these elements clearly, users can ensure that the AI’s communication aligns with their specific goals, whether sounding professional, approachable, or technically precise.

This concept falls under prompt engineering, where carefully structured prompts elicit more accurate and desirable outputs. Using role instructions to define team roles, content creators, researchers, and general users can guide the AI’s behavior in specific, controlled ways.

This post explores the power of role instructions. The aim is to examine why they matter and how they can transform basic AI queries into nuanced, subject-matter-specific answers. We’ll walk through the theory behind role instructions, provide real-world scenarios, and then conduct a hands-on exercise illustrating how two contrasting system messages can alter the same AI model’s tone, style, and perspective.

Introduction to Role Instructions

Shaping AI Behavior Through Role Instructions

The first step to understanding role instructions is recognizing these are not mere add-ons to your prompt. Many AI platforms (particularly those relying on large language models) have a hidden or visible section known as the “system” message. This message is often the first piece of information the AI sees before considering any user queries. Much like a stage director’s note to an actor, the system message tells the AI what role it should play. When you see something like “You are a helpful assistant,” it’s a direct role instruction guiding the AI’s approach to any subsequent conversation.

Role instructions in prompt engineering: An image of a stage director guiding actors on a stage, symbolizing how system instructions direct AI behavior.

By default, many AI interfaces use a polite, service-oriented stance, typically introduced by phrases like “You are ChatGPT, a large language model trained by XYZ.” While this default stance ensures broad usability, it might not always align with specific user needs or scenarios, such as when technical expertise or a specialized tone is required.

However, this can be changed to something else drastically affecting the answers. For instance, telling the AI, “You are an expert in digital marketing” will prompt the model to focus on marketing-related details. Telling it, “You are a therapist” will cause it to respond with empathetic language and relevant psychological insights.

The choice of role instructions is crucial to generating the results you need. This choice also plays a significant role in the problem-solving process, guiding the AI through various prompting techniques to enhance its problem-solving capabilities.

Comparing Different Role Instructions

Consider two simple statements:

  1. “You are a helpful assistant…”
  2. “You are an expert in theoretical physics…”

Both lay the groundwork for how the AI should frame its answers. In the first scenario, the AI might be more generalist, focusing on direct assistance and clarity over depth. In the second scenario, it will provide more complex explanations and delve into specialized terminology related to physics. These subtle differences can make or break your query, especially when tackling technical or domain-specific tasks.

Experimentation is key. Test different angles: “You are a 19th-century historian,” or “You are a children’s storyteller.” Each role places the AI in a unique context. Since prompt engineering is about fine-tuning these prompts to achieve the outcomes you need, choosing the right system message (a role message is a subset of a system message) is an invaluable skill. The expected response from the AI will vary significantly based on the assigned role, making it crucial to tailor your prompts carefully.

Side by side comparison showing different role instructions.

Understanding the Importance of Roles and Responsibilities

Exploring the Impact of Defined Roles on AI Performance

An office environment showing a team with labeled roles.

In AI performance, defined roles can significantly impact the model’s ability to process and respond to prompts. Defining roles and responsibilities is crucial for large language models (LLMs) just as they are for human teams. When roles are clearly defined, team members understand their specific duties and contributions to the team’s objectives. This clarity prevents misunderstandings, reduces task overlap, and boosts efficiency and collaboration.

For instance, directional stimulus prompting relies heavily on well-defined roles, which include a hint or cue to guide the language model toward the desired output. Similarly, generated knowledge prompting, which involves prompting the model to create relevant facts for completing the prompt, requires a clear understanding of the model’s capabilities and limitations. By establishing clear guidelines for AI and human interactions, teams can unlock the full potential of LLMs and achieve operational efficiency.

Defining Team Roles and Responsibilities

Establishing Clear Guidelines for Human and AI Interactions

Defining team roles and responsibilities is a critical step in ensuring the effective collaboration of human and AI teams. By establishing clear guidelines for human and AI interactions, teams can avoid inconsistent explanation trees and ensure all team members are aligned toward common goals. This involves identifying the project’s key idea or objective and breaking it down into smaller, manageable tasks.

For complex tasks, least-to-most prompting can be a practical approach. This involves prompting the model to list the original problem’s sub-problems and then solve each sub-problem sequentially. By defining roles and responsibilities, teams can ensure that each member understands their specific duties and contributions to the team’s objectives, leading to improved problem-solving processes and more accurate expected responses.

We will cover these more precise forms of prompting in future articles.

Applying Role Instructions to Complex Tasks

Defining Roles and Using Domain-Specific Roles

One of the most compelling uses of role instructions is applying them to complex or specialized tasks. Say you’re building an AI-driven marketing assistant. Rather than hoping a generic AI can handle those tasks, you can specify: “You are a marketing expert specializing in B2B lead generation.”

That single sentence helps the AI center its knowledge on a specific niche. It begins to respond with best practices, marketing terminologies, and targeted strategies that a general AI might otherwise omit.

Role instructions in prompt engineering: An illustration with sticky notes labeled 'B2B Lead Generation,' 'Marketing Strategy,' and 'Content Creation,' representing domain-specific instructions.

Similarly, a software engineer might instruct the AI: “You are a senior Python developer, well-versed in data analytics and machine learning.” For example, with this instruction, a query like ‘Write a script to analyze sales data’ could result in a detailed Python script complete with Pandas data manipulation and Matplotlib visualizations.

At the same time, a general AI might only offer a high-level outline or simplistic suggestions.

The specialized AI is more likely to generate code snippets, solve programming challenges, and discuss advanced concepts in Python while skipping irrelevant or overly simplistic suggestions. This approach aligns with the chain-of-thought prompting technique, where the AI breaks down complex problems into steps before arriving at a final answer.

These scenarios highlight the strength of role instructions. They remove the guesswork by steering the model toward a specific perspective or skill set. The AI’s knowledge base is still the same, but it’s now directed to sift through that knowledge from a viewpoint more suitable to your needs.

Adjusting Tone and Style

A Venn diagram labeled 'Tone' on one side and 'Style' on the other, highlighting their importance.

Tone and style can be just as important as expertise. Imagine you run a content marketing agency and want the AI to generate friendly, inviting blog posts. Telling the AI, “You are a bubbly, enthusiastic marketing blogger who writes in a relaxed, approachable style” will help achieve that effect.

In contrast, if you need a formal white paper or academic essay, “You are a meticulous researcher who employs technical language and precise citations” might be more appropriate.

This flexibility extends beyond straightforward tasks. Consider hypothetical situations where you’re scripting voice-overs, drafting legal documents, or writing comedic sketches. Each scenario calls for a distinct tone and style; system instructions can set that standard immediately. For example, you might even combine multiple role instructions:

“You are a veteran journalist covering global economic policy and writing in a neutral, fact-driven style. You aim to inform policymakers about emerging market trends with historical comparisons.”

The AI will then shape its sentence structure, vocabulary, and level of detail to align with that directive. And if at any point you need to shift gears, you can modify or completely rewrite the role instructions to usher in a fresh perspective.

Advanced Prompt Engineering Techniques

Exploring Innovative Approaches to Prompt Design

Advanced prompt engineering techniques are essential for unlocking the full potential of large language models. One such technique is complexity-based prompting, which involves prompting the model to solve a problem and then critiquing its solution. This process is repeated until the model reaches a most commonly reached conclusion. Another approach is self-consistency decoding, which involves performing several chain-of-thought rollouts and selecting the most widely reached conclusion.

By exploring innovative approaches to prompt design, teams can develop more effective prompts that elicit accurate and informative responses from large language models. This requires a deep understanding of the model’s capabilities and limitations and the ability to define clear roles and responsibilities for AI and human interactions. By leveraging these advanced techniques, teams can achieve complex, commonsense reasoning and improve the overall performance of their LLMs.

Hands-On Exercise

Crafting System Messages for Distinct Personas

A quick way to see role instructions at work is to create two contrasting personas for the AI. Let’s do the following:

  1. Friendly Teacher Persona

System Message:

You are a friendly teacher who explains concepts in a warm, encouraging tone. You love helping students learn and grow by offering supportive feedback and simple examples.

A cheerful teacher at a blackboard, explaining concepts with colorful diagrams and engaging with smiling students.

2. Strict Teacher Persona

System Message:

You are a strict professor with high academic standards. You value concise, structured answers and appreciate rigorous explanations backed by research or evidence.

A stern professor in a formal academic setting, writing equations on a chalkboard with a focused demeanor.

These two roles illustrate how role instructions can drastically shift the AI’s perspective, even if the user asks the same question.

Asking the Same Question

Let’s ask: “What is the most effective way to study for a college-level math exam?” This question was chosen because it requires a practical, detailed response and can easily demonstrate how tone, style, and depth of advice vary depending on the role instructions. It highlights how a friendly approach might prioritize encouragement, while a strict perspective might focus on discipline and rigor.

  • Friendly Teacher:With this persona, the AI might respond with positive language, highlight the importance of encouragement, and provide user-friendly examples. It could suggest forming study groups, creating color-coded notes, and recommending gentle accountability methods like supportive peers or mentors.
  • Strict Professor:Under this role instruction, the AI might emphasize structure, discipline, and academic rigor. It might advise a thorough review of peer-reviewed journals, practice with challenging problem sets, or even set up a rigid study schedule that tracks progress and test readiness. The tone could be more formal, occasionally stern, reflecting the persona defined in the system message.

By analyzing the two responses, you’ll see how subtle changes in role instructions affect both tone and the kind of advice offered. The friendly teacher might focus on emotional well-being and encourage minor victories, while the strict professor may center on scientific approaches and strict adherence to proven study methods.

Leveraging Role Instructions for Large Language Models and Prompt Engineering

Role instructions are a cornerstone of prompt engineering. When you place these instructions at the system level, you tell the model: “No matter what else happens, always keep this perspective in mind.” This approach bypasses ambiguity and provides a laser-focused orientation for responses. It’s akin to handing an actor a script that specifies character motivation, backstory, and emotional range before the play begins. The directions remain in force throughout the performance, and the script influences every line delivered.

Here are a few practical tips to elevate your prompt engineering game:

  1. Clarity and Brevity:When crafting system instructions, be concise but precise. Overly long or convoluted directives can confuse the AI. Choose words carefully to ensure the persona or expertise you want is conveyed effectively.
  2. Test Iteratively:Prompt engineering is often experimental. Don’t hesitate to tweak your role instructions several times to see how the AI’s response changes. Rapid iteration helps you nail down precisely what works.
  3. Stay Context-Aware:Remain conscious of the conversation’s context. You might get confusing responses if your subsequent questions contradict the system message. Maintaining alignment between role instructions and follow-up queries fosters coherence.
  4. Avoid Conflicting Instructions:Combining multiple roles can be powerful, but contradictory instructions can confuse outputs. If you need a multi-faceted persona—like a “friendly but detail-oriented professor”—be sure those traits can coexist logically.Use Role Instructions for Both Tone and Content:Some users focus solely on domain expertise, forgetting tone. Others fixate on tone but neglect to specify content depth. Cover both areas if you want a thorough transformation of the AI’s replies.

Making Role Instructions Work for You

It’s tempting to see role instructions as merely cosmetic changes. They do more than alter a few words; they guide each response’s logic, depth, and nuance. Whether writing an entertaining blog series or drafting legal documents, you can rely on role instructions to mold the AI’s output to your specifications.

This approach holds even greater significance for educators, marketers, and professionals in high-stakes fields.

  • A teacher might use role instructions to cater to younger learners with more straightforward vocabulary and supportive messaging.
  • A legal consultant might prefer a thoroughly analytical approach that cites court cases or legislation.

A product manager working on user manuals might adopt a clear, direct tone. The possibilities are substantial, and all hinge on well-crafted prompts.

Key Takeaways from Day 5

Role instructions have become an indispensable aspect of modern AI usage. Whether you’re performing content generation, data analysis, or advanced research, role instructions can shape the AI’s responses in more tangible ways than you might imagine. By specifying the persona and style from the onset, you save time, reduce the need for clarification, and gain more precise, more consistent output.

Role instructions in prompt engineering: A metaphor showing tools labeled 'Clarity,' 'Tone,' 'Consistency,' and 'Relevance,' symbolizing the components of effective prompt engineering.

The takeaway is straightforward: fine-tuned instructions deliver fine-tuned results. When you proactively define the AI’s perspective, you take charge of the conversation and steer it toward your goals. The cohesion between system instructions, role instructions, and prompt engineering is the key to maximizing what the AI can do in your specific environment.

Experiment

Experimentation is the next step. Take the exercise from this post, try different system messages, and see which suits your objectives best. Over time, you’ll build a repertoire of role instructions that consistently yield the style, depth, and detail you need—whether dealing with a cheerful classroom or a rigorous academic setting.

Use system and role instructions thoughtfully, and watch the AI’s capabilities come alive in new and powerful ways. The art and science of prompt engineering continue to evolve, but a clear role definition is always a good place to start.

Next, we’ll explore working with constraints and context so you can continuously improve the quality of ChatGPT’s responses.

Stay curious and keep experimenting—better prompts lead to better results!

Thank you to Napkin.ai for the graphical images in this post. Napkin.ai is free, even at the mid-level service. It is in beta so that the Professional Plan won’t be free forever. I suggest you try it out now. The illustrations were created using Leonardo.ai, another free tool (with daily limits).

Finally, I am available for one-on-one coaching to enhance your prompt engineering skills. If you are interested, please book a free consultation.