Assigning Roles

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.