Cloudflare Code Sandbox

The Jupyter MCP Server can execute code in a Cloudflare Sandbox, a container Cloudflare runs at the edge. Execution is routed through the code-sandboxes cloudflare engine.

tip

For the full, engine-level credential and parameter reference, see the Cloudflare sandbox guide in the code-sandboxes documentation.

Requirements

Install the Cloudflare extra:

pip install "jupyter-mcp-server[cloudflare]"

Cloudflare's own SDK is a TypeScript Workers binding, which a Python process cannot hold. This engine therefore drives the sandbox bridge: a reference Worker that Cloudflare publishes, which exposes the SDK over HTTP. Deploy it once:

npm create cloudflare -- sandbox-bridge \
  --template=cloudflare/sandbox-sdk/bridge/worker

The deployment returns the bridge's workers.dev URL and generates the key it accepts. Both are required:

Environment variable	Description
`CLOUDFLARE_SANDBOX_API_URL`	URL of the deployed sandbox bridge Worker
`CLOUDFLARE_SANDBOX_API_KEY`	Key the bridge was deployed with

See the sandbox bridge documentation for the Worker itself.

Configuration

Select the Cloudflare engine with SANDBOX_VARIANT=cloudflare:

SANDBOX_VARIANT=cloudflare
CLOUDFLARE_SANDBOX_API_URL=https://sandbox-bridge.your-subdomain.workers.dev
CLOUDFLARE_SANDBOX_API_KEY=your-bridge-api-key

Or via the command line:

jupyter mcp start \
  --transport streamable-http \
  --sandbox-variant cloudflare \
  --port 4040

MCP client configuration:

{
  "mcpServers": {
    "jupyter": {
      "command": "uvx",
      "args": ["jupyter-mcp-server@latest"],
      "env": {
        "SANDBOX_VARIANT": "cloudflare",
        "CLOUDFLARE_SANDBOX_API_URL": "https://sandbox-bridge.your-subdomain.workers.dev",
        "CLOUDFLARE_SANDBOX_API_KEY": "your-bridge-api-key"
      }
    }
  }
}

note

Each snippet runs in a process of its own, so x = 1 is gone by the next call. Combine the statements that need each other into a single cell, or keep state in a file — the sandbox filesystem persists. Rich display data (figures, HTML) is not returned; outputs come back as text.

Requirements​

Configuration​

Requirements

Configuration