​
Overview

You can customize the system prompt in two ways:
  1. Extend the default system prompt with additional instructions
  2. Override the default system prompt entirely
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.
To add additional instructions to the default system prompt: 
const extendSystemMessage = `
REMEMBER the most important RULE:
ALWAYS open first a new tab and go first to url wikipedia.com no matter the task!!!
`;

​
Override System Prompt

Not recommended! If you must override the default system prompt, make sure to test the agent yourself.
Anyway, to override the default system prompt: 
import { Agent } from "browsernode";
import { ChatOpenAI } from "browsernode/llm";

const overrideSystemMessage = `
You are an AI agent that helps users with web browsing tasks.

[Your complete custom instructions here...]
`;

// Create agent with custom system prompt
const agent = new Agent(
    {
        task: "Your task here",
        llm: llm,
        overrideSystemMessage: overrideSystemMessage,
    }
);

​
Extend Planner System Prompt

You can customize the behavior of the planning agent by extending its system prompt: 
const extendPlannerSystemMessage = `
PRIORITIZE gathering information before taking any action.
Always suggest exploring multiple options before making a decision.
`;

// Create agent with extended planner system prompt
const llm = new ChatOpenAI(model: "gpt-4o");
const plannerLLM = new ChatOpenAI(model: "gpt-4o-mini");

const agent = new Agent(
    {
        task: "Your task here",
        llm: llm,
        plannerLLM: plannerLLM,
        extendPlannerSystemMessage: extendPlannerSystemMessage,
    }
);