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Kitsune

Lets AI agents operate Firefox-family browsers through background tabs, approvals, and configurable read, draft, or act modes.

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Install Kitsune

Pick your client, then add it in one click or paste the config.

STDIOPython
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "kitsune": {
      "command": "uvx",
      "args": [
        "--from",
        "kitsune-browser-mcp",
        "kitsune"
      ],
      "env": {
        "KITSUNE_MODE": "YOUR_VALUE_HERE",
        "KITSUNE_USER_TABS": "YOUR_VALUE_HERE"
      }
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Values are written into the snippet above so you can paste it as is. They never leave your browser.

We couldn’t confirm it starts correctly

We ran the install command but it didn't respond within our test window — this can mean a slow first-time install rather than a real problem.

uvx --from kitsune-browser-mcp kitsune

No response to initialize.

This is an experimental automated check and can have false negatives — missing environment variables, a slow cold install, etc. It doesn’t necessarily mean something’s wrong. Last checked 6d ago.

Overview

kitsune connects MCP clients to Firefox, Zen, or LibreWolf through a browser extension and local bridge. Agents can work in their own background tabs while your active tab remains in front, and can request temporary access when a task needs one of your tabs. Its Playwright MCP-compatible core tools are joined by user-approval and resume tools, with additional capabilities available after you allow them. Reach for kitsune when an agent needs your existing browser session and logged-in accounts without installing Playwright, Chromium, or WebDriver.

Use cases

  • Research several sites in background tabs
  • Fill out a form without submitting it
  • Compare products using an existing browser login
  • Ask for approval before submitting or paying
  • Resume tasks after a sign-in or CAPTCHA

Key features

  • Firefox, Zen, and LibreWolf browser control
  • Background tabs that keep the user's tab in front
  • Playwright MCP-compatible core tools
  • Read, draft, and act operating modes
  • User approval and tab handoff controls
  • Local bridge with browser extension connectivity

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 2d ago

Recent health check succeeded.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 6d ago via OSV.dev · kitsune-browser-mcp (PyPI)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

GitHub stars36Stargazers on the source repository.
Last commit2d agoMost recent push to the default branch.
Install checkInconclusiveDidn't respond in our test window — often a slow first install.

How Kitsune works

What kitsune does

kitsune lets MCP-compatible coding agents operate Firefox-family browsers that you already use: Firefox, Zen, and LibreWolf. The agent can open background tabs, inspect pages, navigate its own tabs, and perform browser tasks through a set of 25 core tools aligned with Playwright MCP's familiar tool names. Prompts written for Playwright MCP can therefore be reused.

The browser extension keeps the agent's work separate from the tab you are using. Tabs opened by the agent are available for agent actions, while your tabs and tabs created by other agents are read-only by default. When the agent needs to work in one of your tabs, it requests access through the extension's toolbar popup. You can approve, decline, or take the tab back.

How it works

A local MCP process communicates with the browser extension through kitsune's local bridge. The bridge starts when the MCP server runs, so the browser only needs the extension installed and open. Agent tabs open in the background, allowing you to continue using the browser. If you begin typing in an agent-owned tab, the agent waits.

The extension popup shows the connection state, pending approval requests, and controls for reclaiming tabs or closing the agent's tabs. Idle agent tabs close automatically after five minutes by default; that interval can be changed from the popup.

Kitsune supports three operating modes. read restricts the agent to reading, draft permits form filling without clicking or submitting, and act allows the broader action set. Risk-sensitive operations such as form submission, payment pages, JavaScript, and cookie access can use an approval policy. For sign-ins, CAPTCHAs, or decisions that require the user, browser_ask_user pauses for input and browser_resume continues the task.

Setup and configuration

Install uv, add the kitsune browser extension to Firefox, Zen, or LibreWolf, and register the local server with your MCP client. The server command is:

bash
uvx --from kitsune-browser-mcp kitsune

For Claude Code, registration can be done with:

Terminal
claude mcp add --scope user kitsune -- uvx --from kitsune-browser-mcp kitsune

Keep the browser running while the agent uses it. A separate browser profile is recommended for agent work, with only the accounts required for the task signed in.

Set KITSUNE_MODE to read, draft, or act to limit the agent's operating scope. Set KITSUNE_USER_TABS=writable if you explicitly want the agent to modify your tabs without requesting access first.

Tools and capabilities

  • Read open tabs and operate agent-created background tabs.
  • Use the 25 core Playwright MCP-compatible browser tools.
  • Ask the user for sign-in, CAPTCHA, or other human decisions.
  • Pause and resume after user interaction.
  • Request controlled access to a user-owned tab.
  • Use additional page-text, form, batch, and download tools after they are enabled.
  • Keep user tabs read-only by default.

Limitations and notes

Kitsune targets Firefox, Zen, and LibreWolf rather than Chromium browsers. It does not require Playwright, Chromium, WebDriver, or Firefox startup flags, but it does require the browser extension and a running browser.

The agent cannot automatically write to protected user tabs. Approved access can be withdrawn with Take back, and the extension does not provide the agent with the user's physical mouse or keyboard. The writable setting removes the approval step, so it should be enabled only when that behavior is intended.

Prompt injection is not prevented by kitsune. Review its security guidance before using sensitive accounts, and ask the agent to confirm before sending messages, making purchases, or deleting data.

Read the full README View source on GitHub

Reviews

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Frequently Asked Questions about Kitsune

kitsune is an MCP server that connects AI agents to Firefox, Zen, and LibreWolf through a browser extension and local bridge. Its main tools let agents read tabs, control background browser tabs, ask users for input, and resume after approval. It supports Playwright MCP-compatible core browser tools and configurable read, draft, and act modes.

Install uv, add the kitsune extension to Firefox, Zen, or LibreWolf, then register `uvx --from kitsune-browser-mcp kitsune` with your MCP client. Claude Code can use `claude mcp add --scope user kitsune -- uvx --from kitsune-browser-mcp kitsune`. Keep the browser open while the agent runs.

Yes, kitsune works with Firefox, Zen, and LibreWolf. Install its browser extension, keep the browser open, and run the local MCP server through uvx. It connects through the extension and local bridge, so Firefox does not need remote-debugging startup flags.

Not by default. User-owned tabs are read-only, so writes fail unless you approve a handoff in the toolbar popup. You can take the tab back at any time, or set `KITSUNE_USER_TABS=writable` to allow writes without asking first.

Use `KITSUNE_MODE=draft` to let the agent fill forms without clicking or submitting them. For broader use, an ask-before-act policy can require approval for form submissions, payment pages, JavaScript, and cookie access.

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