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PromptBeginner5 minmarkdown
Nano Banana Pro
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Customize
System Prompt
DocumentationCloud API
Overview You can customize the system prompt by extending the
SystemPrompt class. Internally, this adds extra instructions to the default system prompt.
Custom system prompts allow you to modify the agent’s behavior at a fundamental level. Use this feature carefully as it can significantly impact the agent’s performance and reliability.
Basic Customization Create a custom system prompt by inheriting from the base class. Copy
from browser_use import Agent, SystemPrompt class MySystemPrompt(SystemPrompt): def important_rules(self) -> str: # Get existing rules from parent class existing_rules = super().important_rules() # Add your custom rules new_rules = """ 9. MOST IMPORTANT RULE: - ALWAYS open first a new tab and go to wikipedia.com no matter the task!!! """ # Make sure to use this pattern otherwise the exiting rules will be lost return f'{existing_rules}\n{new_rules}'
Using Custom System Prompt Apply your custom system prompt when creating an agent: Copy
from langchain_openai import ChatOpenAI # Initialize the model model = ChatOpenAI(model='gpt-4o') # Create agent with custom system prompt agent = Agent( task="Your task here", llm=model, system_prompt_class=MySystemPrompt )
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