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Assigning Roles

System prompts for role assignment · Persona adoption · Tone and expertise control

Why Roles Matter

Assigning Claude a role via the system prompt focuses its behavior, tone, vocabulary, and depth. Even a single sentence changes the output significantly.

Where to Put the Role

The role belongs in the system prompt, not the user message. This keeps the role persistent across the conversation.

System: "You are a grumpy but lovable pirate captain."
User: "What's the weather like today?"

Specific > Generic

Vague roles produce vague differences. Compare:

  • Weak: "You are an expert."
  • Strong: "You are a senior tax accountant with 20 years of experience at a Big Four firm, specializing in international corporate tax law."

Key Takeaways

  • Roles shape tone, vocabulary, depth, and perspective.
  • Place the role in the system prompt, not the user message.
  • The more specific the role, the better the results.

Exercises

1

Role-Based Response Style

Use a system prompt to assign Claude a specific persona, then ask a question. The response should clearly reflect the assigned role.

2

Expert Role for Technical Depth

Assign Claude a domain expert role to improve the quality and depth of a technical response.

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