Methods

Complete reference for all 55 BAP protocol methods organized by category.

BAP defines 55 methods across 13 categories. All methods use JSON-RPC 2.0 request/response format over WebSocket.

Lifecycle (3)

Method	Description
initialize	Handshake — returns server capabilities. Accepts optional sessionId for session persistence
notifications/initialized	Client confirms ready (notification, no response)
shutdown	Clean shutdown of the connection

Browser (2)

Method	Description
browser/launch	Launch browser instance
browser/close	Close browser instance

browser/launch parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | browser | "chromium" \| "firefox" \| "webkit" | "chromium" | Browser engine | | channel | string | — | Playwright channel (e.g., "chrome", "msedge") | | headless | boolean | true | Run in headless mode | | args | string[] | — | Additional browser arguments | | proxy | object | — | Proxy configuration | | downloadsPath | string | — | Directory for downloads | | userDataDir | string | — | Persistent user data directory | | cdpUrl | string | — | Connect to existing browser via CDP |

Page (8)

Method	Description
page/create	Create new page. Params: url, viewport, userAgent, contextId
page/navigate	Navigate to URL. Supports observe fusion param
page/reload	Reload current page
page/goBack	Navigate back in history
page/goForward	Navigate forward in history
page/close	Close page
page/list	List all open pages
page/activate	Bring page to front

page/navigate parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | url | string | — | Target URL (required) | | waitUntil | "load" \| "domcontentloaded" \| "networkidle" | "load" | When to consider navigation complete | | timeout | number | 30000 | Navigation timeout in ms | | observe | AgentObserveParams | — | Fused observation after navigation |

Actions (13)

Method	Description
action/click	Click element
action/dblclick	Double-click element
action/type	Type text character by character
action/fill	Fill input field (clears existing value first)
action/clear	Clear input field
action/press	Press keyboard key (e.g., "Enter", "Tab")
action/hover	Hover over element
action/scroll	Scroll page or element
action/select	Select dropdown option
action/check	Check checkbox
action/uncheck	Uncheck checkbox
action/upload	Upload file to file input
action/drag	Drag element to target

All action methods accept a selector parameter using any of the 10 selector types.

Common action parameters

| Parameter | Type | Description | |-----------|------|-------------| | pageId | string | Target page (defaults to active page) | | selector | BAPSelector | Element to interact with | | timeout | number | Operation timeout in ms |

Observations (7)

Method	Description
observe/screenshot	Take screenshot (JPEG default, PNG optional)
observe/accessibility	Get accessibility tree
observe/dom	Get page HTML (sensitive content redacted)
observe/element	Get element properties
observe/pdf	Generate PDF of the page
observe/content	Get page text, HTML, or markdown
observe/ariaSnapshot	Get ARIA snapshot in YAML format

Storage (5)

Method	Description
storage/getState	Get cookies + localStorage
storage/setState	Set cookies + localStorage
storage/getCookies	Get cookies for current domain
storage/setCookies	Set cookies
storage/clearCookies	Clear all cookies

Emulation (4)

Method	Description
emulate/setViewport	Set viewport width and height
emulate/setUserAgent	Set custom user agent string
emulate/setGeolocation	Set geolocation coordinates
emulate/setOffline	Toggle offline mode

Dialog, Tracing, Events (4)

Method	Description
dialog/handle	Accept or dismiss a browser dialog
trace/start	Start a Playwright trace recording
trace/stop	Stop trace and return data
events/subscribe	Subscribe to specific event types

Context (3)

Browser contexts provide isolated sessions with separate cookies and storage.

Method	Description
context/create	Create new browser context with optional viewport, locale, permissions
context/list	List all active contexts
context/destroy	Destroy a context and all its pages

Frame (3)

Method	Description
frame/list	List all frames in the current page
frame/switch	Switch to an iframe (by selector or frame ID)
frame/main	Switch back to the main frame

Stream + Approval (2)

Method	Description
stream/cancel	Cancel a streaming response
approval/respond	Respond to a human-in-the-loop approval request

Discovery (1)

Method	Description
discovery/discover	Discover WebMCP tools exposed by the current page

See the WebMCP guide for details on tool discovery.

Agent (3)

The agent methods are composite operations optimized for AI agent workflows. They batch multiple lower-level operations into single requests.

Method	Description
agent/act	Execute a sequence of action steps with retry logic, conditions, and pre/post observation
agent/observe	Get an AI-optimized page snapshot with interactive elements, stable refs, and optional annotation
agent/extract	Extract structured data from the page using a JSON Schema

agent/act parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | steps | ExecutionStep[] | — | Sequence of steps to execute (1-50) | | pageId | string | active page | Target page | | stopOnFirstError | boolean | true | Halt on first failure | | timeout | number | — | Global timeout for entire sequence | | preObserve | AgentObserveParams | — | Run observe before steps (fusion) | | postObserve | AgentObserveParams | — | Run observe after steps (fusion) |

agent/observe parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | includeAccessibility | boolean | — | Include full accessibility tree | | includeScreenshot | boolean | — | Include base64 screenshot | | includeInteractiveElements | boolean | — | Include interactive elements with refs | | maxElements | number | 50 | Max elements to return | | filterRoles | string[] | — | Filter to specific ARIA roles | | responseTier | "full" \| "interactive" \| "minimal" | "full" | Response compression tier | | incremental | boolean | — | Return only changes since last observation | | includeWebMCPTools | boolean | — | Discover WebMCP tools on the page | | annotateScreenshot | boolean \| AnnotationOptions | — | Add Set-of-Marks style annotation |

agent/extract parameters

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | instruction | string | — | Natural language description of what to extract | | schema | ExtractionSchema | — | JSON Schema defining the output structure | | mode | "single" \| "list" \| "table" | "single" | Extraction mode | | selector | BAPSelector | — | Limit extraction scope to a container | | includeSourceRefs | boolean | — | Include source element references |

Fusion Operations

Six optimizations that eliminate redundant roundtrips:

Fusion	How It Works	Savings
observe-act-observe	preObserve/postObserve in agent/act	Eliminates 2 extra WebSocket calls
navigate-observe	observe param in page/navigate	Eliminates 1 extra call
incremental observe	incremental: true returns only changes	Reduces payload size
selector caching	Cached CSS paths for ref lookups	Faster resolution
response tiers	full / interactive / minimal	Up to 80% smaller payloads
speculative prefetch	Fire-and-forget observe after click/navigate	Pre-warms cache