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.
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.
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
Browser Interaction Examples
You can use browser_session to directly interact with page elements using CSS selectors:
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
You can use Pydantic for the tool parameters:
Domain Restrictions
Limit tools to specific domains:
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.
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.
❌ Wrong: Using browser: Browser
✅ Correct: Using browser_session: BrowserSession
Key Points
- Use
browser_session: BrowserSession - not browser: Browser
- Use
async functions - recommended for consistency with browser operations
- Return
ActionResult - not plain strings (though strings work, ActionResult provides more control)
- Parameter names must match exactly - see Available Objects for the full list of injectable parameters