cloakbrowser-mcp

cloakbrowser-mcp is a Model Context Protocol browser automation server that runs upstream @playwright/mcp with the CloakBrowser Chromium binary. It provides Playwright MCP-compatible tools through a thin CloakBrowser bridge for npm and Docker users over stdio or Streamable HTTP.

Documentation: swimmwatch.github.io/cloakbrowser-mcp

Cross-platform checks cover npm on Linux x64/arm64, macOS arm64/x64, and Windows x64 across Node.js 22-26. Docker images are built and smoke-tested for linux/amd64 and linux/arm64.

The server is intentionally thin:

• upstream Playwright MCP owns browser tool schemas, descriptions, and responses;
• this package generates a Playwright MCP config that points launchOptions.executablePath to CloakBrowser;
• the bridge exposes upstream tools unchanged;
• the only local tools are cloakbrowser_binary_info and cloakbrowser_bridge_info.

Version compatibility

| cloakbrowser-mcp | @playwright/mcp | CloakBrowser | Node.js | Platform | | ---------------- | --------------- | ------------ | --------- | ----------------------------------------------------------------------------------------- | | 1.4.0 | ^0.0.76 | ^0.3.32 | >=22.12 | npm on Linux x64/arm64, macOS arm64/x64, Windows x64; Docker linux/amd64, linux/arm64 | | 1.3.0 | ^0.0.75 | ^0.3.31 | >=20 | Docker linux/amd64, Node.js local | | 1.2.7 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.6 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.5 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.3 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.2 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.1 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.2.0 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.1.0 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.0.2 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.0.1 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local | | 1.0.0 | ^0.0.75 | ^0.3.30 | >=20 | Docker linux/amd64, Node.js local |

See Version Compatibility for the maintained compatibility table.

Registry visibility

cloakbrowser-mcp publishes server.json to the official MCP Registry. GitHub's github.com/mcp registry is a separate curated discovery surface, so an official MCP Registry release may not appear there immediately.

Verify the current official registry entry and GitHub MCP visibility probe with:

npm run registry:check

Use npm run registry:check:strict only when GitHub MCP listing visibility should be treated as a required release gate.

Run from npm

npx -y cloakbrowser-mcp@latest --help
npx -y cloakbrowser-mcp@latest doctor
npx -y cloakbrowser-mcp@latest doctor --json
npx -y cloakbrowser-mcp@latest
npx -y cloakbrowser-mcp@latest --transport streamable-http --http-port 3000
npx -y cloakbrowser-mcp@latest --transport streamable-http --http-protocol https --https-cert ./cert.pem --https-key ./key.pem

Requires Node.js 22.12 or newer. The first real browser action may download the CloakBrowser binary unless it is already cached. Use doctor for local diagnostics before connecting an MCP client. It checks the Node.js engine, project metadata, upstream Playwright MCP resolution, and CloakBrowser binary metadata without starting the bridge or downloading a browser. The default transport is stdio. Streamable HTTP binds to 127.0.0.1 by default, serves MCP at /mcp, and exposes fixed GET /healthz and GET /readyz probes. Use --http-protocol https with --https-cert and --https-key or --https-pfx for direct TLS. If --http-auth-token is set, the probes require the same Authorization: Bearer ... header as MCP requests. For the complete generated CLI flag reference, see the published CLI Reference.

Run from Docker

docker pull swimmwatch/cloakbrowser-mcp:latest
docker run --rm --init -i \
  -v "$PWD/artifacts:/data" \
  swimmwatch/cloakbrowser-mcp:latest

docker run --rm --init -p 127.0.0.1:3000:3000 \
  -v "$PWD/artifacts:/data" \
  swimmwatch/cloakbrowser-mcp:latest \
  --transport streamable-http --http-host 0.0.0.0 --http-port 3000

curl http://127.0.0.1:3000/healthz
curl http://127.0.0.1:3000/readyz

For direct HTTPS from the container, mount your TLS files and select HTTPS:

docker run --rm --init -p 127.0.0.1:3000:3000 \
  -v "$PWD/artifacts:/data" \
  -v "$PWD/certs:/certs:ro" \
  swimmwatch/cloakbrowser-mcp:latest \
  --transport streamable-http --http-host 0.0.0.0 --http-port 3000 \
  --http-protocol https --https-cert /certs/cert.pem --https-key /certs/key.pem

The Docker image is based on the pinned official Playwright MCP image, installs the bridge under /opt/cloakbrowser-mcp, writes artifacts to /data by default, and is published for linux/amd64 and linux/arm64. The same tags are also published to ghcr.io/swimmwatch/cloakbrowser-mcp.

MCP client configuration

npm

{
  "mcpServers": {
    "cloakbrowser": {
      "command": "npx",
      "args": ["-y", "cloakbrowser-mcp@latest"],
      "env": {
        "PLAYWRIGHT_MCP_OUTPUT_DIR": "/tmp/cloakbrowser-artifacts",
        "PLAYWRIGHT_MCP_HEADLESS": "true"
      }
    }
  }
}

Docker

{
  "mcpServers": {
    "cloakbrowser": {
      "command": "docker",
      "args": [
        "run",
        "--rm",
        "--init",
        "-i",
        "-v",
        "/tmp/cloakbrowser-artifacts:/data",
        "swimmwatch/cloakbrowser-mcp:latest"
      ]
    }
  }
}

Configuration

Use upstream PLAYWRIGHT_MCP_* variables for browser, artifact, timeout, network, and tool capability settings. Cloak-specific bridge toggles use CLOAK_PLAYWRIGHT_MCP_*. CLI flags are documented in the generated CLI Reference.

Common variables:

| Variable | Default | Description | | --- | --- | --- | | CLOAK_PLAYWRIGHT_MCP_TRANSPORT | stdio | MCP transport exposed by the bridge: stdio or streamable-http. | | CLOAK_PLAYWRIGHT_MCP_HTTP_PROTOCOL | http | Streamable HTTP listener protocol: http or https. | | CLOAK_PLAYWRIGHT_MCP_HTTP_HOST | 127.0.0.1 | Streamable HTTP bind host. | | CLOAK_PLAYWRIGHT_MCP_HTTP_PORT | 3000 | Streamable HTTP bind port. | | CLOAK_PLAYWRIGHT_MCP_HTTP_ENDPOINT | /mcp | Streamable HTTP endpoint path. | | CLOAK_PLAYWRIGHT_MCP_HTTP_AUTH_TOKEN | unset | Optional Bearer token for Streamable HTTP. | | CLOAK_PLAYWRIGHT_MCP_HTTP_SESSION_BACKEND | memory | Session metadata backend. Only memory is implemented in this release. | | CLOAK_PLAYWRIGHT_MCP_HTTP_SESSION_IDLE_TTL_MS | 3600000 | Idle TTL for Streamable HTTP sessions. | | CLOAK_PLAYWRIGHT_MCP_HTTP_SESSION_MAX | 32 | Maximum active Streamable HTTP sessions in one process. | | CLOAK_PLAYWRIGHT_MCP_HTTPS_CERT | unset | TLS certificate PEM path for HTTPS Streamable HTTP. | | CLOAK_PLAYWRIGHT_MCP_HTTPS_KEY | unset | TLS private key PEM path for HTTPS Streamable HTTP. | | CLOAK_PLAYWRIGHT_MCP_HTTPS_PFX | unset | TLS PFX/PKCS12 path for HTTPS Streamable HTTP. | | CLOAK_PLAYWRIGHT_MCP_HTTPS_PASSPHRASE | unset | Passphrase for an encrypted HTTPS key or PFX. | | CLOAK_PLAYWRIGHT_MCP_LOG_LEVEL | info | Streamable HTTP operational log level: trace, debug, info, warn, error, fatal, or silent. | | PLAYWRIGHT_MCP_BROWSER_ENGINE | cloak | cloak uses CloakBrowser. playwright uses the upstream Playwright MCP browser runtime. | | PLAYWRIGHT_MCP_HEADLESS | true | Runs Chromium headless. | | PLAYWRIGHT_MCP_OUTPUT_DIR | .playwright-mcp | Artifact directory for npm usage. Docker defaults to /data. | | PLAYWRIGHT_MCP_OUTPUT_MODE | stdout | Upstream output mode, either stdout or file. | | CLOAK_PLAYWRIGHT_MCP_CONSOLE_FALLBACK | true | Enables the compatibility patch for console messages. | | CLOAK_PLAYWRIGHT_MCP_STEALTH_ARGS | true | Adds CloakBrowser default stealth launch arguments. | | CLOAK_PLAYWRIGHT_MCP_EXTRA_ARGS | unset | Comma-separated or JSON array of extra Chromium launch arguments. |

The old CLOAKBROWSER_MCP_* variables are not supported.

Tools

The upstream Playwright MCP tool list is authoritative. This project does not reimplement or re-document upstream browser schemas in source code.

Local tools:

• cloakbrowser_binary_info returns CloakBrowser package, platform, cache, and resolved binary data.
• cloakbrowser_bridge_info returns bridge metadata, upstream package/version, and local tool names.

Development

npm install
npm run build
npm test
npm run docker:build
npm run docker:smoke
npm run server:validate
npm run bridge:compare -- cloakbrowser-mcp:dev --report bridge-parity-report.json

Documentation starts at docs/getting-started.md. Contributor material is grouped under docs/contributor-guide.md.