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BAM-DevCrew

Firefox DevTools MCP

by BAM-DevCrew
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TypeScript
Local

Server Configuration

Describes the environment variables required to run the server.

NameRequiredDescriptionDefault
DEBUGNoSet to '*' to include verbose debug logs.
START_URLNoOpen this URL on start.
TOOL_PRESETNoSelect which tool modules to enable: slim, basic (default), developer, mozilla, or all.basic
ENABLE_SCRIPTNoDeprecated, use --tool-preset developer or --tools ... script debugging. Selects the developer tool preset. Set to 'true' to enable.
ANDROID_PACKAGENoAndroid app package name. Default org.mozilla.firefox. Other packages: org.mozilla.firefox_beta for Firefox Beta, org.mozilla.fenix for Firefox Nightly, org.mozilla.fenix.debug for Firefox Nightly Debug, org.mozilla.geckoview_example for geckoview.org.mozilla.firefox
MARIONETTE_PORTNoMarionette port for connect-existing mode, default 2828.2828
CONNECT_EXISTINGNoAttach to an already-running Firefox instead of launching a new one. Set to 'true' to enable.
FIREFOX_HEADLESSNoRun without UI (headless mode). Set to 'true' to enable.
ACCEPT_INSECURE_CERTSNoIgnore TLS errors. Set to 'true' to enable.
ENABLE_PRIVILEGED_CONTEXTNoDeprecated, use --tool-preset mozilla or --tools ... privileged prefs. Selects the mozilla tool preset. Requires MOZ_REMOTE_ALLOW_SYSTEM_ACCESS=1. Set to 'true' to enable.
MOZ_REMOTE_ALLOW_SYSTEM_ACCESSNoRequired for privileged context and prefs modules. Set to '1' to enable.

Capabilities

Features and capabilities supported by this server

CapabilityDetails
tools
{}
resources
{}

Tools

Functions exposed to the LLM to take actions

NameDescription
list_pagesA

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

new_pageA

Open new tab at URL. Returns tab index.

navigate_pageA

Navigate selected tab to URL.

select_pageA

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

close_pageA

Close tab by index.

take_snapshotA

Capture DOM snapshot with stable UIDs. Retake after navigation.

resolve_uid_to_selectorA

Resolve UID to CSS selector. Fails if stale.

clear_snapshotA

Clear snapshot cache. Usually not needed.

click_by_uidA

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

hover_by_uidB

Hover over element by UID.

fill_by_uidB

Fill text input/textarea by UID.

drag_by_uid_to_uidB

Drag element to another (HTML5 drag events).

fill_form_by_uidA

Fill multiple form fields at once.

upload_file_by_uidB

Upload file to file input by UID.

screenshot_pageA

Capture page screenshot as base64 PNG.

screenshot_by_uidA

Capture element screenshot by UID as base64 PNG.

list_downloadsA

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

clear_downloadsA

Clear the tracked downloads buffer.

set_download_behaviorA

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

accept_dialogA

Accept browser dialog. Provide promptText for prompts.

dismiss_dialogA

Dismiss browser dialog.

navigate_historyA

Navigate history back/forward. UIDs become stale.

set_viewport_sizeA

Set viewport dimensions in pixels.

get_firefox_outputA

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_infoA

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

restart_firefoxA

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

install_extensionA

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

uninstall_extensionA

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

screencast_startA

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_stopA

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

evaluate_scriptA

Execute JS function in page. Prefer UID tools for interactions.

Prompts

Interactive templates invoked by user choice

NameDescription

No prompts

Resources

Contextual data attached and managed by the client

NameDescription

No resources

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