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Headless Colab MCP Server

colab-mcp is a FastMCP server for controlling Google Colab notebooks through a secure, headless WebSocket architecture. Agents can create, edit, run, and inspect notebook cells without browser automation or UI scraping.


Features

  • Headless Operation — Run notebook operations through a secure WebSocket proxy

  • Zero Browser Management — No Chromium, browser profiles, or DOM scraping

  • ML-Ready Tooling — Workspace setup, dataset handling, and pipeline execution

  • Structured Results — Typed stdout, stderr, file paths, and error details

  • FastMCP Integration — Clean MCP server interface for tool composition


Related MCP server: JupyterMCP

Architecture

The server uses two cooperating layers:

ColabSessionProxy

  • Starts a localhost WebSocket server

  • Generates a one-time connection URL with mcpProxyToken and mcpProxyPort

  • Waits for an authenticated Colab tab to attach

NotebookController

  • Exposes the stable MCP tool surface

  • Discovers proxy capabilities from the connected Colab frontend

  • Maps server-owned tools to proxy-backed cell operations

  • Falls back to direct runtime execution only when needed


Requirements

Requirement

Version

Python

3.13+

uv

Latest

Google Colab

Active browser session


Installation

uv sync
uv run colab-mcp

Configuration

Add this to your MCP configuration:

{
  "mcpServers": {
    "colab-mcp-local": {
      "command": "uv",
      "args": ["run", "colab-mcp"],
      "cwd": "${workspaceFolder}",
      "timeout": 30000
    }
  }
}

API Reference

Core Notebook Tools

Tool

Description

connect_colab(notebook_url?)

Initialize connection and retrieve proxy URL

list_colab_cells()

List all cells in the notebook

read_colab_cell(cell_id)

Read a specific cell

write_colab_cell(code, cell_id?, mode?)

Write code to a cell

run_colab_cell(cell_id?, wait?, timeout_seconds?)

Execute a cell

run_colab_code(code, mode?, wait?, timeout_seconds?)

Write and execute code in one step

get_colab_output(cell_id?)

Retrieve execution output

save_colab_notebook()

Save the notebook

run_runtime_code(code)

Execute code directly in the runtime

ML Workflow Tools

Tool

Description

setup_ml_workspace(packages)

Install packages and create standard data directories

fetch_remote_dataset(download_url, extract_to)

Download and extract datasets

execute_ml_pipeline(code_block)

Execute Python blocks with structured results


Usage

  1. Start the MCP server.

  2. Call connect_colab to get a connect_url, proxy_token, and proxy_port.

  3. Paste the connect_url into an active Colab tab.

  4. Wait for the proxy connection to establish.

  5. Run notebook operations through the MCP tools.

Example

uv run colab-mcp
connect_colab()
setup_ml_workspace(["pandas", "scikit-learn"])
fetch_remote_dataset(url, "/content/data")
execute_ml_pipeline(training_code)
get_colab_output()

Development & Verification

PYTHONPATH=src python scripts/smoke_test.py
PYTHONPATH=src py -m pytest
cat RELEASE_CHECKLIST.md

Test coverage

  • Proxy capability discovery

  • Native Colab argument mapping

  • Cell ID extraction

  • ML tool routing through proxy

  • Execution result normalization


License

This project is licensed under the Apache License 2.0.


Acknowledgments

This headless WebSocket proxy architecture was inspired by the open-source work provided by the Google Colab team.

Available Tools

13 tools
connect_colabD

Inputs: notebook_url. Returns: backend, message, connected, proxy_port, +6 more

execute_ml_pipelineD

Inputs: code_block (required). Returns: status, stderr, stdout, traceback, +4 more

fetch_remote_datasetD

Inputs: extract_to (required), download_url (required). Returns: status, stderr, stdout, cell_id, +7 more

get_colab_outputD

Inputs: cell_id. Returns: status, stderr, stdout, cell_id, +7 more

list_colab_cellsD

Inputs: no named parameters. Returns: result

open_colab_browser_connectionA

Checks whether a Google Colab proxy session is already connected. Returns a boolean representing whether the headless proxy connection is available.

Inputs: no named parameters. Returns: result

read_colab_cellD

Inputs: cell_id (required). Returns: code, cell_id, outputs, preview, +2 more

run_colab_cellD

Inputs: wait, cell_id, timeout_seconds. Returns: status, stderr, stdout, cell_id, +7 more

run_colab_codeD

Inputs: code (required), mode, wait, timeout_seconds. Returns: status, stderr, stdout, cell_id, +7 more

run_runtime_codeD

Inputs: code (required). Returns: status, stderr, stdout, cell_id, +7 more

save_colab_notebookD

Inputs: no named parameters. Returns: message, success, notebook_url

setup_ml_workspaceD

Inputs: packages (required). Returns: status, stderr, stdout, cell_id, +7 more

write_colab_cellD

Inputs: code (required), mode, cell_id. Returns: code, cell_id, outputs, preview, +2 more

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    TDQS

    D1.7/5.0

    Scored across 13 tools

    Disambiguation2/5

    Several tools appear to serve similar purposes: run_colab_cell, run_colab_code, run_runtime_code, and execute_ml_pipeline all seem to execute code, while connect_colab and open_colab_browser_connection overlap in establishing/checking a connection. Without descriptions, it's hard for an agent to pick the right tool.

    Naming Consistency3/5

    Most tools follow a verb_noun snake_case pattern, but there's inconsistency: some include 'colab' (e.g., list_colab_cells) while others do not (e.g., setup_ml_workspace, fetch_remote_dataset). Also, the verbs vary widely, making the naming feel less systematic than a strict verb_noun convention.

    Tool Count4/5

    13 tools is within a reasonable range for a Colab-focused server. However, the presence of four overlapping execution tools inflates the count and suggests some consolidation could improve the set without losing functionality.

    Completeness3/5

    The tool surface covers core cell operations (read, write, run, output) and notebook saving, but lacks obvious lifecycle operations like deleting a cell or creating a notebook. The ML-related tools (setup workspace, fetch dataset, pipeline) add breadth but also introduce unclear boundaries and gaps, such as no explicit tool for managing datasets beyond fetching.

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