Kitsune

Bring your coding agent into Firefox—and keep working alongside it.

Kitsune lets AI agents like Claude Code, Codex, Pi, and OpenCode use the Firefox, Zen, or LibreWolf browser you already have open. Your sessions, cookies, and extensions stay in place. No Playwright, Chromium, or WebDriver required.

Research in background tabs, prepare form drafts, and continue browser tasks with an agent you already use—not a separate browser or built-in AI assistant.

Why Kitsune?

• Work alongside your agent. Agent-created tabs open in the background. Writes to a tab you are actively using are held, and closing your own tabs requires a separate confirmation step. These protections reduce interference; OS-level clicks and site-opened popups still have focus and input limitations.
• Choose how much to delegate. Configure KITSUNE_MODE=read, draft, or act to limit the available tools and bridge requests. Draft mode allows supported field input without click or submit tools; sites may still autosave edits. The default is act, not a restricted mode. See Task modes.
• Recover without blindly repeating work. With the optional parallel capability, interrupted batch, parallel, and workflow calls can be resumed without resending successful writes. Uncertain writes require an observation before retrying. Checkpoints are temporary and do not survive a bridge restart.

What can it do?

• Research the web. Search, read pages, and summarize findings with links.
• Interact with websites. Click, type, select options, and fill forms—even on sites you're already signed into.
• Capture and extract. Take screenshots or turn page content into text and Markdown.
• Work across tabs. Keep research and tasks in separate tabs without replacing the page you're using.

_{A real browser session, captured with Kitsune and sped up.}

How do I use it?

1. Connect once. Install uv, then follow the MCP setup for your agent below. Install the browser extension in Firefox, Zen, or LibreWolf: the signed build installs once, while the developer build (needed for browser_js) is a temporary add-on.

2. Keep your browser open. Kitsune starts its shared bridge automatically. Ask your agent to check the connection before your first task.

3. Ask in plain language. For example:

   Research these three products in new background tabs and compare them with source links. Leave my current tab alone.

   Inspect this page's form and fill a draft. Don't submit it yet.

   Open Hacker News in a background tab and summarize the top three stories with links.

   For an enforced draft-only tool surface, configure KITSUNE_MODE=draft before starting the MCP client; asking in plain language does not change the mode.

Use a dedicated browser profile and only give access to accounts the agent needs. Ask for confirmation before sending, purchasing, or deleting anything. The opt-in ask-before-act policy makes the bridge hold submits, payment pages, JavaScript, and cookie access until the agent repeats the call with a confirmation token. That second step is not proof of human approval, and these controls do not prevent prompt injection. Read the security guidance before using sensitive accounts.

MCP setup

All clients launch the same local stdio server: uvx --from kitsune-browser-mcp kitsune. Choose one setup method for each client you use. Several clients can share the same bridge; keep their Kitsune versions and install sources consistent.

CLI registration: Claude Code, Codex, and Pi

Claude Code — available in every project with --scope user:

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

Codex CLI — registers the server in ~/.codex/config.toml:

codex mcp add kitsune -- uvx --from kitsune-browser-mcp kitsune

Pi — uses built-in MCP support with user-level configuration by default:

pi mcp add kitsune -- uvx --from kitsune-browser-mcp kitsune
pi mcp list

Add --local before kitsune to register Pi's server only for the current project. In an already running Pi session, run /reload, then /mcp to inspect the connection. If an MCP adapter extension overrides Pi's built-in support, follow that extension's configuration instructions instead.

OpenCode

Merge this into ~/.config/opencode/opencode.json (global) or opencode.json in your project root. OpenCode uses an mcp object and a command array, not mcpServers:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "kitsune": {
      "type": "local",
      "command": ["uvx", "--from", "kitsune-browser-mcp", "kitsune"],
      "enabled": true
    }
  }
}

JSON configuration: Pi, Claude Desktop, and Cursor

These clients share the same mcpServers format. As an alternative to CLI registration where available, merge the following entry into your client's config; keep any existing servers:

{
  "mcpServers": {
    "kitsune": {
      "command": "uvx",
      "args": ["--from", "kitsune-browser-mcp", "kitsune"]
    }
  }
}

Restart or reconnect your client after configuring it, then ask it to call browser_status. With the browser extension loaded, the response should include "extension_connected": true. GUI apps may need the full path returned by which uvx instead of uvx if they do not inherit your shell's PATH.

Kitsune registers a 14-tool lean surface by default. Set the environment variable KITSUNE_TOOL_PRESET=full for the other 16 core tools: check, submit form, hover, keypress, scroll, JavaScript, waits, dialogs, uploads, Markdown, back/forward, console and workflows (see Lean tool preset).

For Codex's TOML alternative, environment variables, version pinning, and upgrades, see Installation.

For the details: Tools · Configuration · Troubleshooting · Updating · API reference · Development

For architecture, product trade-offs, and the wider browser MCP landscape, see Positioning.

MIT · Based on ZenLink and ZenLink-MCP by Jay-Quan. Credits · License