Firefox DevTools MCP server

Read from the package source without running it. The installed server may list more.

• accept_dialog

  Accept browser dialog. Provide promptText for prompts.

• clear_console_messages

  Clear collected console messages.

• clear_downloads

  Clear the tracked downloads buffer.

• clear_snapshot

  Clear snapshot UIDs. Usually not needed.

• click_by_uid

  Click element by UID. Set dblClick for double-click.

• close_firefox_session

  Ends the browser session. If the server connected to your existing Firefox, this releases the connection and leaves Firefox running. If the server started Firefox itself, this closes it. Call this when the browser task is complete and no further browser interaction is expected.

• close_page

  Close tab by index.

• console

  Read and clear console messages.

• debugging

  Inspect scripts and set logpoints (Firefox 153+).

• dismiss_dialog

  Dismiss browser dialog.

• downloads

  Monitor and manage file downloads.

• drag_by_uid_to_uid

  Drag element to another (HTML5 drag events).

• enable_debugger

  Enable the JS debugger for the current page. Required before set_logpoint works. Requires Firefox 153+.

• evaluate_privileged_scriptwrite action

  Execute JS function in a privileged (chrome) browsing context. Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1 env var. Get context ids from list_privileged_contexts.

• evaluate_scriptwrite action

  Run a JS function in the page and return its result. Prefer this for targeted reads (a value, text, computed style, whether an element exists) instead of a full take_snapshot. Use the UID interaction tools for clicking, typing, and filling.

• fill_by_uid

  Fill text input/textarea by UID.

• fill_form_by_uid

  Fill multiple form fields at once.

• get_firefox_info

  Get information about the current Firefox instance configuration, including binary path, environment variables, and output file location.

• get_firefox_output

  Retrieve Firefox output (stdout/stderr including MOZ_LOG, warnings, crashes, stack traces). Returns recent output from the capture file. Use filters to focus on specific content.

• get_firefox_prefs

  Get Firefox preference values via a privileged API. Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1 env var.

• get_logpoint_results

  Get the results collected by a logpoint since it was set.

• get_network_request

  Get request details by ID, including the response body (and request body when present). Large text bodies are truncated inline; binary bodies are summarized. URL lookup as fallback.

• get_page_text

  Get the visible text of the page (document.body.innerText). Caps at maxLength (default 20000 chars); saveTo saves the full text to a file.

• get_script_source

  Get the source code of a JavaScript file loaded in the page. Requires enable_debugger to have been called.

• hover_by_uid

  Hover over element by UID.

• input

  Interact with the page via UID-based clicks, typing, key presses, drag, and uploads.

• install_extension

  Install a Firefox extension using WebDriver BiDi webExtension.install command. Supports installing from archive (.xpi/.zip), base64-encoded data, or unpacked directory.

• launch

  Restart Firefox under a different launch configuration.

• list_console_messages

  List console messages, filterable by level, time, text, source. Caps at limit (default 50); saveTo saves all matches to a file.

• list_downloads

  List downloads tracked since startup, including status and saved file path.

• list_network_requests

  List network requests, returning IDs for get_network_request. Filter by url/method/status; caps at limit (default 50); saveTo saves all matches to a file.

• list_pages

  List open tabs (index, title, URL). Selected tab is marked.

• list_privileged_contexts

  List privileged (privileged) browsing contexts. Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1 env var. Use restart_firefox with env parameter to enable.

• list_scripts

  List all JavaScript files currently loaded in the page. Requires enable_debugger to have been called.

• management

  Inspect Firefox options and logs, and close the browser.

• navigate_history

  Navigate history back/forward. UIDs become stale.

• navigate_page

  Navigate selected tab to URL.

• network

  List and inspect network requests, and control the HTTP cache.

• new_page

  Open new tab at URL. Returns tab index.

• pages

  Open, navigate, select, and close pages.

• prefs

  Get and set Firefox preferences.

• press_key

  Press a single key, optionally with modifiers, to submit, dismiss, navigate or trigger a shortcut. Not for entering text: use fill_by_uid instead.

• profiler

  Start, stop, and query the performance profiler.

• profiler_is_active

  Check whether the Firefox profiler is currently recording.

• profiler_start

  Start the Firefox profiler. Provide either a preset name or explicit recording options (entries, interval, features, threads). Cannot combine both. Valid presets: ….

• profiler_stop

  Stop the Firefox profiler and save the recorded profile to a file in the downloads directory. Returns the path to the saved file, or null when nothing was saved.

• remove_logpointwrite action

  Remove a previously set logpoint.

• resolve_uid_to_selector

  Resolve UID to CSS selector. Fails if the element is gone.

• restart_firefox

  Restart Firefox with different configuration. Allows changing binary path, environment variables, and other options. All current tabs will be closed.

• screencast

  Record screencasts of the page viewport (Firefox 154+).

• screencast_start

  Start recording a screencast (video) of the current page viewport, saving the output to a file in the downloads directory. Returns a screencast id to pass to screencast_stop. Multiple recordings can run at once.

• screencast_stop

  Stop an in-progress screencast recording started with screencast_start and finalize the video file. Returns the path to the saved file.

• screenshot

  Capture screenshots of the page or specific elements.

• screenshot_by_uid

  Capture element screenshot by UID as base64 PNG.

• screenshot_page

  Capture viewport screenshot as base64 PNG. Set fullPage for the whole scrollable document.

• script

  Evaluate arbitrary JavaScript in the page context.

• select_page

  Select active tab by index, URL, or title. Index takes precedence.

• select_privileged_context

  Select a privileged browsing context by ID and set WebDriver Classic context to "chrome" . Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1 env var.

• set_download_behavior

  Control how downloads are handled: allow (save to a destination folder), deny (cancel), or reset to default. Avoids the native save-file dialog. Requires a recent Firefox.

• set_firefox_prefs

  Set Firefox preferences at runtime a privileged API. Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1 env var.

• set_logpoint

  Set a logpoint at a specific location. When execution reaches that line, the expression is evaluated and the result is stored without pausing. Use get_logpoint_results to retrieve collected values. Requires enable_debugger to have been called.

• set_network_cache

  Control the HTTP cache. Use behavior='bypass' so every request goes to the network \u2014 useful for performance measurement and for verifying a change that a cached asset would otherwise hide. Applies to the currently selected tab unless scope='global'. Persists until set back to 'default' or Firefox shuts down.

• set_viewport_size

  Set viewport dimensions in pixels.

• snapshot

  Capture accessibility/DOM snapshots and resolve UIDs.

• take_snapshot

  Capture DOM snapshot with stable UIDs. A UID stays valid across snapshots until its element is removed or the page navigates. Output caps at maxLines (default 100); scope with selector or dump the full tree with saveTo.

• type_text

  Type text key by key into the focused element, optionally followed by a key such as Enter. Use fill_by_uid to set the value of a known input; use this for elements that only react to real typing, such as autocomplete fields and rich text editors.

• uninstall_extension

  Uninstall a Firefox extension using WebDriver BiDi webExtension.uninstall command. Requires the extension ID returned by install_extension or obtained from list_extensions.

• upload_file_by_uidwrite action

  Upload file to file input by UID.

• utilities

  Handle dialogs, history navigation, and viewport sizing.

• webextension

  Install and uninstall web extensions.

• Code scan3 source files scanned20/25
• –Live reliabilityno gateway calls yet and no remote to proben/a
• –Tool poisoningtools not inspected (local package is not executed); not countedn/a
• Auth qualitylocal package, no credentials required12/15
• Maintenancelast push 0 days ago15/15
• Maintainer identityregistry namespace matches repository owner; GitHub account older than a year9/10

Firefox DevTools MCP: common questions

Is Firefox DevTools MCP server safe?

Yes, by our scan: it is graded A (86/100). Read the Firefox DevTools MCP safety report

How do I install Firefox DevTools MCP?

It runs on your machine. Copy the Claude Code, Claude Desktop or Cursor config from the install section.

Does Firefox DevTools MCP need an API key?

No secret keys are declared. It reads 2 settings from the environment.

Is Firefox DevTools MCP maintained?

The last commit was in the last day (2026-09-22). The latest release is v0.10.4.