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Examples:
  • deterministic clicks
  • file handling
  • calling APIs
  • human-in-the-loop
  • browser interactions
  • calling LLMs
  • get 2fa codes
  • send emails
  • Playwright integration (see GitHub example)
  • …
Simply add @tools.action(...) to your function. 
from browser_use import Tools, Agent, ActionResult

tools = Tools()

@tools.action(description='Ask human for help with a question')
async def ask_human(question: str) -> ActionResult:
    answer = input(f'{question} > ')
    return ActionResult(extracted_content=f'The human responded with: {answer}')

agent = Agent(task='...', llm=llm, tools=tools)
  • description (required) - What the tool does, the LLM uses this to decide when to call it.
  • allowed_domains - List of domains where tool can run (e.g. ['*.example.com']), defaults to all domains
The Agent fills your function parameters based on their names, type hints, & defaults.
Common Pitfall: Parameter names must match exactly! Use browser_session: BrowserSession (not browser: Browser). The agent injects special parameters by name matching, so using incorrect names will cause your tool to fail silently. See Available Objects below for the correct parameter names.

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Available Objects

Your function has access to these objects:
  • browser_session: BrowserSession - Current browser session for CDP access
  • cdp_client - Direct Chrome DevTools Protocol client
  • page_extraction_llm: BaseChatModel - The LLM you pass into agent. This can be used to do a custom llm call here.
  • file_system: FileSystem - File system access
  • available_file_paths: list[str] - Available files for upload/processing
  • has_sensitive_data: bool - Whether action contains sensitive data

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Browser Interaction Examples

You can use browser_session to directly interact with page elements using CSS selectors: 
from browser_use import Tools, Agent, ActionResult, BrowserSession

tools = Tools()

@tools.action(description='Click the submit button using CSS selector')
async def click_submit_button(browser_session: BrowserSession):
    # Get the current page
    page = await browser_session.must_get_current_page()

    # Get element(s) by CSS selector
    elements = await page.get_elements_by_css_selector('button[type="submit"]')

    if not elements:
        return ActionResult(extracted_content='No submit button found')

    # Click the first matching element
    await elements[0].click()

    return ActionResult(extracted_content='Submit button clicked!')
Available methods on Page:
  • get_elements_by_css_selector(selector: str) - Returns list of matching elements
  • get_element_by_prompt(prompt: str, llm) - Returns element or None using LLM
  • must_get_element_by_prompt(prompt: str, llm) - Returns element or raises error
Available methods on Element:
  • click() - Click the element
  • type(text: str) - Type text into the element
  • get_text() - Get element text content
  • See browser_use/actor/element.py for more methods

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Pydantic Input

You can use Pydantic for the tool parameters: 
from pydantic import BaseModel

class Cars(BaseModel):
    name: str = Field(description='The name of the car, e.g. "Toyota Camry"')
    price: int = Field(description='The price of the car as int in USD, e.g. 25000')

@tools.action(description='Save cars to file')
def save_cars(cars: list[Cars]) -> str:
    with open('cars.json', 'w') as f:
        json.dump(cars, f)
    return f'Saved {len(cars)} cars to file'

task = "find cars and save them to file"

​
Domain Restrictions

Limit tools to specific domains: 
@tools.action(
    description='Fill out banking forms',
    allowed_domains=['https://mybank.com']
)
def fill_bank_form(account_number: str) -> str:
    # Only works on mybank.com
    return f'Filled form for account {account_number}'

​
Advanced Example

For a comprehensive example of custom tools with Playwright integration, see: Playwright Integration Example This shows how to create custom actions that use Playwright’s precise browser automation alongside Browser-Use.

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Common Pitfalls

The agent injects special parameters by name, not by type. Using incorrect parameter names is the most common cause of tools failing silently.

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❌ Wrong: Using browser: Browser

from browser_use import Tools, ActionResult, Browser

@tools.action('My action')
def my_action(browser: Browser) -> ActionResult:  # WRONG!
    # This will NOT receive the browser session
    pass

​
✅ Correct: Using browser_session: BrowserSession

from browser_use import Tools, ActionResult, BrowserSession

@tools.action('My action')
async def my_action(browser_session: BrowserSession) -> ActionResult:  # CORRECT!
    page = await browser_session.must_get_current_page()
    # Now you have access to the browser
    return ActionResult(extracted_content='Done')

​
Key Points

  1. Use browser_session: BrowserSession - not browser: Browser
  2. Use async functions - recommended for consistency with browser operations
  3. Return ActionResult - not plain strings (though strings work, ActionResult provides more control)
  4. Parameter names must match exactly - see Available Objects for the full list of injectable parameters