Prepare for a FoxMCP meeting with Claude Code: organize tabs, save the project pages, and clear away distractions.

FoxMCP — Firefox Browser Automation via MCP

Connect an MCP-compatible AI assistant to Firefox. Manage tabs and windows, read pages, upload local files, organize bookmarks, search history, and inspect network requests.

FoxMCP has two parts: a Firefox extension and a local Python server. Your AI client talks to the server, which sends commands to the extension.

Privacy: Connected AI clients can access your browser data and run page scripts. Use trusted clients and consider a dedicated Firefox profile. See SECURITY.md for the threat model.

Get the server from PyPI or GitHub releases. Install the matching extension from Firefox Add-ons.

Upgrading: Update the server and extension together, restart shared workers, and refresh your client's tool schemas. Call profiles_list and pass its integer profile_id to every browser tool, even with one profile connected. Rediscover targets after reconnection. See release notes.

FoxMCP or firefox-devtools-mcp?

Both let an AI agent use Firefox. They suit different jobs.

Use FoxMCP to work in your own browser. It is an extension in the Firefox you already run, so the agent sees your open tabs, logged-in sites, bookmarks, history, and containers. Nothing needs a restart, and several agents can share the same Firefox.

Use firefox-devtools-mcp to test or debug a web page. It starts its own Firefox, so the browser is clean and disposable. It offers console, network, debugger, and profiler tools, and it works with Firefox for Android.

firefox-devtools-mcp can also attach to a Firefox that is already running (--connect-existing), but only one started with special remote-control flags. Plain Firefox needs a restart, or a second profile, first.

Sharing Firefox between agents. Start each client with uvx foxmcp --stdio --single-instance so they share one connection. FoxMCP does not lock tabs, so give each agent its own window to keep them from stepping on each other.

Mind the access. In your real session, a connected AI client can reach whatever you can. Use a trusted client, consider a dedicated Firefox profile, and read SECURITY.md.

Quick start

You need Firefox, an MCP client, and uv. Your client starts FoxMCP with uvx foxmcp --stdio; uv manages the Python environment and downloads the package automatically. FoxMCP requires Python 3.10+.

1. Install the Firefox extension

Open FoxMCP on Firefox Add-ons and click Add to Firefox.

Use matching server and extension versions. Click the FoxMCP toolbar icon to see a mismatch warning with both versions inside the popup. No automatic dialog or notification opens. The server also logs a warning. Release-version differences are advisory when protocol IDs match; incompatible protocol IDs prevent the browser connection. Mozilla review can delay the Add-ons version after a GitHub release; to try a version awaiting approval, use the temporary add-on instructions.

2. Connect your AI client

For Claude Code:

claude mcp add foxmcp -- uvx foxmcp --stdio

For Codex:

codex mcp add foxmcp -- uvx foxmcp --stdio

For another MCP client, add a stdio server with command uvx and arguments ["foxmcp", "--stdio"].

Open your AI client so it starts the server. Click the FoxMCP toolbar icon in Firefox and check that it shows a connected status. The extension connects on WebSocket port 8765. If the first browser call arrives before Firefox reconnects, retry it.

For multiple clients or chats, add --single-instance after --stdio to share one browser connection. See stdio setup.

The packaged command includes and enables the example scripts. An explicit FOXMCP_EXT_SCRIPTS overrides them; an empty value disables scripts. To match a particular extension release, use uvx --from foxmcp==VERSION foxmcp --stdio, replacing VERSION with that release's version.

3. Try it

Ask your assistant to discover profiles and choose the intended one before performing browser actions. For example:

List the connected Firefox profiles and their windows/tabs.
Use the profile named Personal for the following task. If the name is ambiguous,
show me the candidates first.
List all open Firefox tabs in that profile.
Open https://example.org in a new tab.
Get the text from the current page.
Take a screenshot of the current tab.

To target a particular tab, right-click it in Firefox's tab bar and choose Tab ID = … (click to copy). Paste the copied tab_id = … into your request. Tab IDs are local to their profile. The copied tab ID does not identify its profile; give the assistant that context too. Rediscover after Firefox restarts.

What you can do

Native tab groups require Firefox 139+. Local file uploads use files readable by the Python server; see loading local files. See the API reference for tool names and parameters.

Other setup options

Install from GitHub release archives

The GitHub installers create a local installation directory. On Linux/macOS, you need Python 3.10+, venv, bash, curl, unzip and sha256sum. On Debian/Ubuntu, install missing prerequisites with sudo apt install python3 python3-venv curl unzip coreutils.

For the GitHub archive installation, run this in a new directory where you want FoxMCP installed:

mkdir foxmcp && cd foxmcp
curl -fSL https://github.com/ThinkerYzu/foxmcp/releases/download/v1.7.0/install-from-github.sh | bash

The installer verifies the release archive checksums, creates venv/, installs Python dependencies, and creates start-foxmcp.sh. It also installs example scripts and a CLAUDE.md template, and offers to connect Claude Code.

For unattended setup, save the installer outside the target directory and run bash /path/to/install-from-github.sh --non-interactive from an empty directory.

Windows (PowerShell 5.1 or newer):
Download both installer scripts into a separate folder, then run the installer from an empty installation folder.
An empty folder has no installer yet, and the installer needs install-xpi.ps1 beside it.
Keeping both outside the target also satisfies the unattended installer's empty-folder check.

Use separate commands below: PowerShell 5.1 cannot parse &&, which was added in PowerShell 7.

New-Item -ItemType Directory foxmcp-installer
$installerBase = 'https://github.com/ThinkerYzu/foxmcp/releases/download/v1.7.0'
Invoke-WebRequest -UseBasicParsing "$installerBase/install-from-github.ps1" -OutFile foxmcp-installer/install-from-github.ps1
Invoke-WebRequest -UseBasicParsing "$installerBase/install-xpi.ps1" -OutFile foxmcp-installer/install-xpi.ps1
New-Item -ItemType Directory foxmcp
Set-Location foxmcp
& ..\foxmcp-installer\install-from-github.ps1 -NonInteractive

Keep the two scripts together and outside the installation folder. If you already have a source checkout, run its scripts/install-from-github.ps1 by absolute path from an empty folder instead. Omit -NonInteractive to enable interactive prompts. The installer creates venv/, installs Python dependencies, creates start-foxmcp.ps1, installs example scripts, and creates a CLAUDE.md template.

Use start-foxmcp.ps1 for a manually started HTTP server. For MCP stdio, configure the client to launch the installed venv\Scripts\python.exe with server\server.py --stdio as arguments, using absolute paths. Set FOXMCP_EXT_SCRIPTS to the installed predefined-scripts directory in the client environment to enable the examples. The PowerShell helper reports the direct Python command if invoked with --stdio.

Start the installed server manually with ./start-foxmcp.sh on Linux/macOS or .\start-foxmcp.ps1 in PowerShell, then use the HTTP setup below.

Run a shared HTTP server

Start one server and leave it running:

uvx foxmcp

With a GitHub archive installation, use its startup script instead. The default ports are 8765 for the extension's WebSocket connection and 3000 for the MCP HTTP endpoint. Check the connected status in the Firefox extension popup.

Register the HTTP endpoint with Claude Code:

claude mcp add --transport http foxmcp http://localhost:3000/mcp/

Or with Codex:

codex mcp add foxmcp --url http://localhost:3000/mcp/

For another MCP client, add an HTTP server with URL http://localhost:3000/mcp/. If the GitHub installer already connected your client, skip registration.

Install from source

You also need Git, make, and zip (on Debian/Ubuntu: sudo apt install git make zip).

git clone https://github.com/ThinkerYzu/foxmcp.git
cd foxmcp
make install
make package

Load the built extension in Firefox, then start the server with make run-server. Continue with HTTP setup above.

Let your client start the server

Use stdio with --single-instance to start the server automatically and share it across chats. Configure each client to launch venv/bin/python server/server.py --stdio --single-instance, using absolute paths. Clients discover and share the browser connection on the extension port. They join an existing server or start a background worker automatically. Closing one chat leaves the others connected. Automatic workers stop after 60 seconds without clients; manually started servers keep running. On Windows, use venv\Scripts\python.exe. See stdio setup.

Configuration

Click the FoxMCP toolbar icon to change extension connection settings. If you change the WebSocket port, change it on both the extension and the server. Host/Port and Reconnect Interval save automatically after a 500ms pause. Reset persists defaults immediately. Retries use a constant interval (1000ms by default, configurable from 100 to 30000ms); there is no manual Reconnect button. Both Popup and Options show actual connection and protocol status. See extension configuration.

With uvx, pass server options after foxmcp:

# Custom WebSocket and MCP HTTP ports
uvx foxmcp --port 9000 --mcp-port 4000

# Hide tool groups from clients
uvx foxmcp --disable-tools bookmarks,history

# Hide a group but keep its screenshot tool
uvx foxmcp --disable-tools tabs --enable-tools tabs_capture_screenshot

For a client-managed stdio server, include the same options in its launch command, for example:

uvx foxmcp --stdio --single-instance --disable-tools bookmarks,history

For a GitHub archive or source installation, the same options follow venv/bin/python server/server.py. Run from that installation directory:

venv/bin/python server/server.py --port 9000 --mcp-port 4000

Use profiles_list first to inspect all connected Firefox profiles, their real names, windows and tabs. Every browser command requires the chosen profile_id alongside its window/tab IDs. Profiles can share the same server port without replacing each other. The server assigns positive integer IDs from 1. IDs change on every reconnect; rediscover after a disconnect or server restart. Update both extension and server for protocol 3. Follow the multiple-profile setup to connect each Firefox instance, then use profile discovery to choose a target.

All 46 tools are enabled by default. Available groups are profiles, windows, tabs, containers, bookmarks, navigation, content, requests, history, and debug. See configuration for client examples and other options.

Firefox containers

Use containers_list to discover named containers and their opaque cookie_store_id values. Pass one to tabs_create to open in that container, or to tabs_list to filter. Use firefox-default for normal browsing. Omission keeps existing behavior; invalid selections fail without opening a fallback tab.

containers_create, containers_update and containers_remove manage persistent profile containers. Removal clears stored site data and refuses containers with open tabs. Containers survive client disconnects. See the API reference for details.

The extension requires contextualIdentities and cookies permissions for container APIs and tab selection. Installation can enable Firefox containers; subsequent disabling is respected. Update both extension and server together.

Predefined scripts

External executable scripts can generate JavaScript for FoxMCP to run in a tab. The release installer configures the examples in predefined-scripts/; the packaged foxmcp command uses its bundled examples by default. Both include DOM summaries, YouTube controls, calendar extraction, and a file-input helper. Ask your assistant which predefined scripts are available.

For your own scripts, set FOXMCP_EXT_SCRIPTS to their directory before starting the server. For example, save this as get-title.sh in that directory and run chmod +x get-title.sh:

#!/bin/bash
# Return the current page title.
echo 'document.title'

Then ask your assistant to run get-title.sh in a tab. Restart the server after adding scripts to refresh the list shown to clients. See the script guide for arguments, setup, and file upload examples.

Troubleshooting

For other errors, run the server in the foreground and inspect its output.

Documentation and development

• Configuration — ports, MCP clients, tool selection and reconnect behavior
• API reference — all tools and parameters
• Scripts — reusable automation and local file uploads
• Request monitoring — filters, response bodies and monitor lifetime
• Development — extension installation, builds, tests and release workflow
• Architecture and protocol — how the components communicate
• Release notes and changelog — updates and upgrade instructions
• Security — trust boundaries and vulnerability reporting

See CONTRIBUTING.md for contribution and test setup guidelines.

Coding agents: Read CLAUDE.md before making changes.

Licensed under the MIT License.