What is a System Prompt?
A system prompt is a special instruction that sets the context, persona, and behavioral guidelines for an AI model. It's typically hidden from users and persists throughout a conversation.
Purpose of System Prompts
System prompts establish the foundation for how the AI should behave.
Define Persona
Establish who the AI is: an assistant, expert, character, etc.
Set Boundaries
Define what the AI should and shouldn't do.
Establish Tone
Specify communication style: formal, casual, technical.
Provide Context
Include domain knowledge or rules specific to your application.
Structure of Effective System Prompts
Well-organized system prompts are easier for models to follow.
Identity Section
Who is the AI? What is its role?
Capabilities
What can the AI do? What tools does it have?
Limitations
What should the AI avoid or refuse?
Guidelines
Specific rules for behavior and responses.
Interactive Builder
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Template Presets
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Identity Section
Not configured
Be specific about expertise level and persona. Include relevant background that shapes responses.
Capabilities
Not configured
List concrete abilities. Use bullet points for clarity. Include any tools or integrations available.
Limitations
Not configured
Explicitly state what the AI should never do. Cover security, privacy, and ethical boundaries.
Guidelines
Not configured
Include formatting preferences, tone requirements, and domain-specific rules.
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Example System Prompt
You are a helpful coding assistant specialized in TypeScript. ## Identity - You are an expert TypeScript developer - You provide clear, concise code examples - You follow best practices and explain trade-offs ## Capabilities - Code review and suggestions - Debugging help - Architecture advice ## Limitations - Do not write code that accesses external APIs - Do not provide financial or legal advice - Always recommend testing for production code ## Guidelines - Use TypeScript strict mode conventions - Prefer functional patterns when appropriate - Include type annotations in examples
Best Practices
- ✓Be explicit about edge cases and error handling.
- ✓Test system prompts with adversarial inputs.
- ✓Version control your system prompts.
- ✓Keep prompts focused—don't overload with instructions.
Key Takeaways
- 1System prompts define the AI's persona and behavior
- 2Structure prompts clearly: identity, capabilities, limitations
- 3Test with edge cases—users will find them
- 4System prompts can be overridden—don't rely solely on them for security