camofox-browser MCP server

A standalone Model Context Protocol server that exposes camofox-browser to any MCP-compatible host — Claude Code, Cursor, etc. — without requiring OpenClaw.

It mirrors the existing OpenClaw plugin 1:1: same 11 tool names, identical JSON-Schema parameters, and the same REST routes. Whether an agent reaches camofox via OpenClaw or MCP, the behavior is identical.

The initial MCP server implementation was contributed by @epicsagas.

Architecture

The MCP server is a thin stdio client over the camofox REST server. Two pieces:

• REST server (server.js) — launches Camoufox, exposes the HTTP API on :9377. Run once, it stays up.
• MCP server (mcp/server.mjs, exposed as the camofox-browser-mcp bin) — translates MCP tool calls into REST calls. Claude Code spawns one per session.

Registering the MCP server does not require being inside the camofox-browser checkout. The examples below work from any directory.

mcp/ is also an independently installable package (@askjo/camofox-browser-mcp, its own package.json). It depends on nothing but @modelcontextprotocol/sdk — no camoufox-js, playwright-core, express, or the ~300MB browser binary download that the core server pulls in. Tool names, JSON-Schema parameters, REST routes, and response shaping are defined in mcp/lib/tool-contracts.mjs, which ships inside the standalone package. The OpenClaw plugin (plugin.ts) imports the same canonical module, so the two hosts cannot drift. See Option D below if you only want the MCP adapter (e.g. pointing CAMOFOX_BASE_URL at a REST server running elsewhere).

1. Start the REST server

Clone the repo and start the server (one-time binary download on first run):

git clone https://github.com/jo-inc/camofox-browser && cd camofox-browser
npm install   # downloads Camoufox (~300MB) on first run
npm start     # → http://localhost:9377

This stays running in the background. It does not need to be your cwd afterwards.

2. Install the camofox-browser-mcp bin

The MCP server is the same for every host — what differs is only the config file you paste into. First, make the camofox-browser-mcp bin available on your PATH. Pick one:

# Option A — npm link (if you have the source checkout; picks up local edits)
cd camofox-browser && npm link

# Option B — global install (no source checkout needed)
npm install -g @askjo/camofox-browser

# Option C — npx (no install; runs the published standalone adapter)
#   Use this wherever a command is expected below.
npx -y @askjo/camofox-browser-mcp

# Option D — MCP adapter only, no core server deps (lightest footprint)
#   Skips camoufox-js/playwright-core/express and the browser binary download —
#   use this if a camofox-browser REST server is already running (locally or
#   remotely) and you only need the stdio adapter.
git clone https://github.com/jo-inc/camofox-browser && cd camofox-browser/mcp
npm install   # installs only @modelcontextprotocol/sdk (~24MB, no postinstall)
npm link      # camofox-browser-mcp now resolves from any directory

Verify the bin resolves from any directory:

which camofox-browser-mcp   # → .../bin/camofox-browser-mcp

3. Register with your host

All five hosts speak standard MCP, so they all run the same camofox-browser-mcp bin. Pick your host's config snippet below.

Claude Code

# CLI (user scope = available in every project)
claude mcp add camofox-browser -s user -- camofox-browser-mcp

Or in ~/.claude.json (user) / .mcp.json (project, checked in):

{
  "mcpServers": {
    "camofox-browser": {
      "command": "camofox-browser-mcp"
    }
  }
}

Codex CLI

~/.codex/config.toml (user) or .codex/config.toml (project, trusted dirs only):

[mcp_servers.camofox-browser]
command = "camofox-browser-mcp"
env = { CAMOFOX_BASE_URL = "http://localhost:9377" }

Antigravity / agy

Global ~/.gemini/config/mcp_config.json or workspace .agents/mcp_config.json:

{
  "mcpServers": {
    "camofox-browser": {
      "command": "camofox-browser-mcp"
    }
  }
}

Cursor

Global ~/.cursor/mcp.json or project .cursor/mcp.json (checked in):

{
  "mcpServers": {
    "camofox-browser": {
      "command": "camofox-browser-mcp"
    }
  }
}

(Or via UI: Settings → Cursor Settings → MCP → Add New MCP Server.)

opencode

opencode.json in the project root, or global ~/.config/opencode/opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "camofox-browser": {
      "type": "local",
      "command": ["camofox-browser-mcp"]
    }
  }
}

Common: env vars and from-source fallback

If you need cookie import or a non-default REST URL, add env. Example for Claude Code:

claude mcp add camofox-browser -s user \
  --env CAMOFOX_BASE_URL=http://localhost:9377 \
  --env CAMOFOX_API_KEY=<key> \
  -- camofox-browser-mcp

For the other hosts, add the same keys to the env / environment field of that host's snippet.

From-source fallback (only if you're inside the checkout and haven't linked the bin):

# Replace `camofox-browser-mcp` with `node /absolute/path/to/mcp/server.mjs`
claude mcp add camofox-browser -- node /Users/you/src/camofox-browser/mcp/server.mjs

⚠️ Always prefer the camofox-browser-mcp bin (options A/B/C/D above). The node ./mcp/server.mjs form is path-dependent — relative paths break outside the checkout.

4. Verify

You should see 11 tools: camofox_create_tab, camofox_snapshot, camofox_click, camofox_type, camofox_navigate, camofox_scroll, camofox_screenshot, camofox_evaluate, camofox_list_tabs, camofox_close_tab, camofox_import_cookies.

Tools

Workflow

Every interaction follows the same shape — snapshot before you act:

1. create_tab({ url }) → tabId
2. snapshot({ tabId }) → element refs (e1, e2, ...)
3. click/type using those refs
4. snapshot again to read the new state
5. close_tab when done

Element refs are unambiguous and preferred over CSS selectors — a selector that matches multiple elements returns 422 strict mode violation, in which case re-snapshot and click by ref.

Environment variables

Troubleshooting

• 503 session_expired / tab create timed out — the REST server's browser session died (often after a prior failed call destabilized it). Restart npm start.
• camofox_scroll returns {ok:true} but the page doesn't move — expected on lazy-load / virtual-scroll pages; the server's mouse.wheel no-ops there. Use camofox_evaluate with window.scrollTo / scrollBy.
• 422 strict mode violation ... resolved to N elements on click — CSS selector matched multiple elements. Re-snapshot and click by element ref.
• 403 Forbidden on camofox_import_cookies — key mismatch between REST server and MCP server, or hitting a remote server without CAMOFOX_API_KEY.
• 401/403 on every tool call, not just cookie import — the REST server has CAMOFOX_ACCESS_KEY set. Set the same CAMOFOX_ACCESS_KEY in the MCP server's env (see table above) — it's forwarded automatically as Authorization: Bearer once set.

Testing (developer)

Two layers, covering different things:

# 1. `test:mcp` installs the standalone adapter's locked dependencies, then
#    runs the in-repository and packed-tarball handshake tests. Neither needs
#    a REST server.
npm run test:mcp

# 2. Mock-HTTP contract tests — verifies the actual REST traffic each tool
#    produces: routes, methods, request bodies, CAMOFOX_ACCESS_KEY/CAMOFOX_API_KEY
#    auth headers, cookie parsing (Netscape file → `{ cookies }` body, never a
#    path), screenshot decoding, and error handling. Mocked REST server — no
#    live camofox-browser process needed. This is what makes the "OpenClaw and
#    MCP send identical requests" claim verifiable, not just asserted.
NODE_OPTIONS='--experimental-vm-modules' npx jest tests/unit/mcp-contracts.test.js

The packed-tarball check installs the generated @askjo/camofox-browser-mcp tarball in an empty directory before its handshake. It catches imports that reach outside the standalone package.