Browser Use

Browser Use

Control the user's existing real Chrome profile, especially for login-dependent work and live UI verification.

Route

1. Use the Codex Chrome or Chrome [Internal] plugin when it is callable in the active session. Installed on disk is not enough.
2. Otherwise prefer the OpenClaw extension-backed mcporter route.
3. Use legacy direct DevTools attachment only as the explicit last fallback.

For mcporter, the MCP call remains the agent-facing control interface. The OpenClaw extension is the transport underneath it, not a separate tool. Set chromeDevtoolsRelay: "require" on the canonical global Chrome server definition to enforce relay-only routing. Keep the caller policy explicit as well:

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MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.<tool>

Seeing an agent request the chrome-devtools MCP tool is therefore expected. A Chrome Allow remote debugging? prompt or a relay-policy error indicates that the extension transport was not used. The shared daemon retains canonical policy; a shell environment prefix alone cannot change that policy.

Never use isolated Chrome, the Codex in-app browser, Playwright, Puppeteer, AppleScript, osascript, generic GUI scripting, or macOS open as a browser-control substitute unless the user explicitly asks for an isolated or new browser. Peekaboo is allowed only for Chrome or extension setup and visible prompts. Login-heavy sites often depend on the real profile's cookies, SSO, device trust, and extensions.

For a rendered-browser bug, prove behavior through this real profile. Treat curl, source inspection, API checks, and isolated test browsers as supporting evidence, not substitutes for live UI proof.

Extension Relay Model

OpenClaw creates a random per-host relay key in its mode-0600 credentials directory. The extension and same-host clients use nonce-bound mutual HMAC proofs. The reusable key is never sent to an unverified loopback listener, placed in a URL, or passed to the child MCP process. Keep credentials out of configuration, command output, chat, logs, and screenshots.

On a same-host relay, mcporter authenticates /json/version and upgrades the same retained socket to /cdp, then gives chrome-devtools-mcp a protected one-use local handoff. Agents still call the standard MCP tools; successful relay routing is what removes direct DevTools attachment and Chrome's approval prompt.

New pairings default to All tabs: every ordinary eligible tab is exposed except tabs explicitly paused in the popup. Existing pairings keep their stored mode. In Selected tabs mode, membership in the Chrome tab group titled OpenClaw is the sharing boundary. Restricted/internal pages, incognito, other profiles, and tabs without an eligible URL remain excluded in both modes.

Topology Boundary

Direct remote Gateway pairing over wss:// lets OpenClaw's Gateway-side browser tool control local Chrome. It does not create a local relay for a local mcporter process. Do not routinely copy remote secrets or build ad-hoc SSH tunnels around this boundary.

If local mcporter cannot authenticate to a local relay, the extension-backed mcporter route is unavailable. Report that clearly or use the labeled legacy fallback; never represent remote Gateway control or direct attachment as local relay success.

Setup and Repair

• Run openclaw browser extension install before Load unpacked. It copies the extension to the stable OpenClaw-owned path, pre-registers that path's deterministic Chrome ID, and prints the path to load. The first native call then pairs automatically for local or browser-node topology.
• Use openclaw browser extension status --json to verify the installed copy, exact origins, and native-host registrations. Status must report no issues and manualSetupRequired: false.
• Confirm Settings reports automatic setup ready and the popup reports Connected. New installs should show All tabs unless the user changes the access mode; no copied pairing string or popup setup is part of the normal local flow.
• A previous native-host miss is cached for the Chrome process. If the extension attempted native messaging before installation, restart Chrome once after installing; repeated retries in the same process cannot repair that cache.
• After pairing or changing the relay route, stop the mcporter daemon before re-running relay-only proof. A Gateway restart can leave the Chrome DevTools child alive with a dead upstream socket; mcporter daemon stop retires it before the next call creates a fresh connection.
• Direct remote Gateway pairing remains an Advanced manual flow. It serves the Gateway browser path and does not create a local relay for local mcporter.

Discovery Timeout and Daemon Configuration

MCPorter discovers the actual relay through openclaw browser extension cdp --json. Even packaged OpenClaw can take more than five seconds to cold-start. In mcporter 0.13.10, discovery failure falls back to port 18799; a timeout can therefore appear as network-error at the wrong endpoint, or as browser_owner_conflict when a later discovery returns the real endpoint. Do not interpret that sequence as proof that another Chrome owner or credential rotation caused the failure.

For the shared Chrome owner, use the OS account's canonical ~/.mcporter/mcporter.json (or mcporter.jsonc only when the JSON file is absent). Merge these fields into its existing Chrome definition, preserving its command, arguments and other settings:

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{
  "chromeDevtoolsRelay": "require",
  "env": {
    "MCPORTER_CHROME_DEVTOOLS_RELAY_TIMEOUT_MS": "20000"
  }
}

The relay timeout bounds each discovery or authentication step; it does not extend the client's total operation deadline. Initial Chrome startup can run several discovery checks before MCP initialization and the requested tool call. On older installed clients, pair the canonical 20000 per-step setting with an explicit --timeout 300000 on the initial call or schema listing. For example:

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MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.list_pages --timeout 300000 --output text

Newer Chrome-specific outer defaults require an upgraded invoking client. Explicit --timeout, MCPORTER_CALL_TIMEOUT, and MCPORTER_LIST_TIMEOUT still override those defaults; a smaller override can cut startup short.

The daemon intentionally strips inherited MCPORTER_CHROME_DEVTOOLS_RELAY_* and OPENCLAW_* controls from the canonical Chrome environment. Shell exports do not update an existing owner and are not a durable fix for a respawn. Put literal values in the canonical definition's env; do not use placeholders that depend on those stripped variables. If an explicit endpoint is necessary, set MCPORTER_CHROME_DEVTOOLS_RELAY_URL there to the verified credential-free HTTP loopback base URL, for example http://127.0.0.1:28799 after verifying that port. This override does not accept a WebSocket CDP URL such as ws://127.0.0.1:28799/cdp. Prefer discovery with a sufficient timeout over a guessed or hardcoded port, especially when several OpenClaw installations coexist.

After changing canonical settings, let active calls drain and run mcporter daemon stop. If stop refuses because calls remain active, wait for them to finish and retry stop; proceed only after it succeeds. The next call starts a daemon with the saved settings, and subsequent respawns use the same configuration. Verify the relay decision with mcporter daemon status --json and repeat the readiness proof below. Check the installed mcporter version before relying on newer timeout defaults or explicit discovery-failure diagnostics; a source fix does not update an already installed binary or running daemon.

Current openclaw browser extension cdp --json emits non-secret metadata by default, but older versions and legacy-bearer options can expose credentials. Prefer mcporter's redacted status for routine diagnostics, never request legacy credentials, and do not dump process arguments. If credential exposure is suspected, rotate the per-host secret and pair again.

Fail-Closed Readiness Proof

Require every condition below before calling the extension route ready:

1. Extension status reports the stable copy and exact native registrations with no issues; Settings says automatic setup ready.
2. The popup says Connected and the intended ordinary tab is not paused. In Selected tabs mode, it must also belong to the OpenClaw group.
3. mcporter has been stopped after pairing, relay-route or canonical-config changes, and the next call has started a fresh daemon.
4. The canonical Chrome definition uses chromeDevtoolsRelay: "require", and a call with MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require succeeds. The canonical policy forbids direct DevTools fallback, so success is positive relay proof.
5. Selection and evaluation both succeed in a known eligible disposable tab.

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MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.list_pages --args '{}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.select_page --args '{"pageId":9}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.evaluate_script --args '{"function":"() => ({title: document.title, href: location.href})"}' --output json

A relay-policy error means the extension transport is unavailable; report or repair it instead of retrying without require. A blocking Allow remote debugging? prompt proves legacy attachment was attempted.

Typical Flow

List pages, select only a shared target, snapshot before acting, and use fresh snapshot UIDs. Prefer DOM snapshots over screenshots unless layout matters.

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MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.list_pages --args '{}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.select_page --args '{"pageId":9}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.take_snapshot --args '{}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.click --args '{"uid":"1_38","includeSnapshot":true}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.fill --args '{"uid":"1_13","value":"text","includeSnapshot":true}' --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.evaluate_script --args '{"function":"() => document.title"}' --output json

For live UI proof, capture the current page state before the action, perform the requested interaction, then snapshot or evaluate the rendered result. Keep secrets out of DOM, input, network, console, and screenshot output. For credential checks, return only safe shape such as present/absent, length, status code, or account/organization label.

If automation is unavailable, report the verification gap instead of silently switching to prohibited or isolated tooling.

Argument and Output Mechanics

--args accepts inline JSON only. It does not read @file. Flag-style named arguments do:

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MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.navigate_page url=@/tmp/target-url.txt --output text
MCPORTER_CHROME_DEVTOOLS_RELAY_POLICY=require mcporter call chrome-devtools.evaluate_script function=@/tmp/probe.js --output json

Treat this as a safety primitive, not just ergonomics. A sign-in URL, magic link, or callback URL is credential-equivalent: write it to a mode-0600 file and pass it by file reference so it never reaches shell history, process arguments, or captured tool output. The same form carries a multi-line JavaScript function without quoting or control-character errors.

Other call mechanics worth knowing before a login flow:

• Generic client defaults are 60 seconds for calls and 30 seconds for listings, separate from the relay's per-step discovery/authentication timeout. Slow initial Chrome startup on older clients needs --timeout 300000 as described above. Choose an explicit timeout for later interactive work when needed.
• take_screenshot with filePath is confined to the server's configured workspace roots and refuses arbitrary paths. Omit filePath, read the base64 image from --output json, and decode it locally.
• new_page can fail with a restricted/unavailable tab when the target is not shared. Navigate an already-shared tab instead of creating one.
• mcporter list <server> --schema prints the real function signatures. Use it rather than guessing parameter names.

Clicks That Do Not Click

A click by uid can return success and still do nothing: some pages bind their handlers so that a synthetic click is ignored. Silence is not proof of action, so verify state after every activation rather than assuming it worked.

When a click no-ops, drive the control from the keyboard with press_key (Tab, Shift+Tab, Enter) and confirm focus with a screenshot before committing. Focus rings are the only reliable evidence of which control is about to receive Enter, and consent screens routinely put the safe-looking prominent button next to a low-emphasis link that is the one you actually want. Blind Enter on such a page picks the wrong control.

Snapshot uid values are invalidated by any navigation or re-render. Re-run take_snapshot and re-resolve the uid after every step; a stale uid reports that the element no longer exists, which is a cue to re-snapshot rather than to retry the same call.

When the Relay Goes Empty Mid-Task

The relay can stop exposing tabs partway through a task because eligible tabs were closed, the current tab became restricted or paused, Selected tabs mode lost its group members, or the extension disconnected. The failure can be quiet: list_pages may return an empty result and later calls time out.

Treat an empty page list as "the relay has no eligible tabs", not "the browser is gone". Confirm Chrome is running, check the popup connection and current-tab Pause/Allow state, then check the access mode. Only Selected tabs mode requires restoring the OpenClaw group. Restarting mcporter cannot repair extension disconnection, tab eligibility, or access policy.

Do not escalate to a full-profile attachment or an isolated browser to route around it. When the task is a sign-in the user is present for, the faster and more honest move is to hand the URL to the browser the user is already sitting at, and if the flow's callback listens on another host, forward that port to the user's machine first. Otherwise report the access gap.

Legacy Fallback: Full-Profile Direct Attachment

Use this only after the callable plugin and authenticated local extension relay are unavailable. It exposes the full real-profile tab set and can show Chrome's blocking Allow remote debugging? prompt.

When a visible, unambiguous Chrome prompt asks to allow the attachment, approve it once, then rerun list_pages. If the prompt is absent, ambiguous, or the retry fails, stop and ask the user or report that Chrome DevTools MCP is unavailable. Do not loop approvals, repeatedly restart Chrome or mcporter, or kill browser processes.

Verify that list_pages shows the intended real-profile tabs before acting. Always label this path as full-profile direct attachment, never as OpenClaw extension relay success.