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Cinch

Runs Python or JavaScript in disposable, gVisor-isolated Cinch sandboxes and returns stdout, stderr, exit code, and duration.

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Install Cinch

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "cinch": {
      "command": "npx",
      "args": [
        "-y",
        "@cinch-codes/mcp"
      ],
      "env": {
        "CINCH_API_KEY": "YOUR_VALUE_HERE",
        "CINCH_TIMEOUT_MS": "YOUR_VALUE_HERE",
        "CINCH_BASE_URL": "YOUR_VALUE_HERE"
      }
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Values are written into the snippet above so you can paste it as is. They never leave your browser.

Automated check passed— started and listed 1 tools correctly (4d ago).

Overview

The cinch MCP server lets an AI assistant execute self-contained Python or JavaScript programs in Cinch-hosted, gVisor-isolated containers. Its `execute_code` tool returns standard output, standard error, exit status, and runtime duration without exposing the local machine, filesystem, or network. Reach for it when an agent needs to run and inspect code safely, using only standard-library functionality. Each execution is isolated, billed per run, and limited by Cinch’s sandbox constraints.

Use cases

  • Run self-contained Python calculations in an isolated environment
  • Execute JavaScript snippets without exposing the local machine
  • Inspect generated code output, errors, and exit status
  • Test standard-library logic within fixed resource limits

Key features

  • Python 3.12 and Node 20 execution
  • gVisor-isolated disposable containers
  • Stdout, stderr, exit code, and duration results
  • No local filesystem or network access
  • Per-execution billing with no subscription floor
  • Configurable API endpoint and client timeout

Tools1

What Cinch lets your agent do. Expand a tool for its parameters.

Verified live~487 tokens of context

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 3d ago

Recent health check succeeded.

8/8 checks healthy over the last 50d

What it can do

From the 1 tool this server returned when we ran it; 1 declare their own safety hints.

Runs commands · 1Makes network requests · 1
Network at startup3 connections
Files written at startupNone
Install scriptsNone
npm provenanceNot published
Package age92 days
Maintainers1

Observed 2026-10-24 in an isolated sandbox. A description of reach, not a security audit.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 12d ago via OSV.dev · @cinch-codes/mcp (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

npm downloads77Package downloads in the last 30 days.
Last commit3mo agoMost recent push to the default branch.
Availability100%Our rolling endpoint + install checks that succeeded.
Install checkPassedOur sandbox started it and listed its tools.
Tools exposed1Callable tools this server registers over MCP.
Directory activity1 viewsConfig copies, upvotes, and views on AllMCPs.

How Cinch works

What cinch MCP server does

The cinch MCP server exposes Cinch’s remote code-execution service to MCP clients. An assistant sends a complete Python or JavaScript program through the execute_code tool, and receives stdout, stderr, the exit code, and execution duration. Programs must print results to stdout if the assistant needs to read them.

Execution happens on Cinch infrastructure rather than on the host running the MCP client. The container uses gVisor isolation, runs as a non-root user, drops capabilities, and has no access to the client machine, local files, or local network. Cinch charges per execution and does not require a subscription minimum.

How it works

The cinch MCP server uses a stdio process launched through npx. The client starts @cinch-codes/mcp, and the server sends execution requests to the Cinch API using the configured API key. npx downloads the package on its first run, so a separate package installation is not required.

Each call starts with a clean environment. State does not carry from one request to the next, so code should be self-contained. Python 3.12 and Node 20 are available, with standard-library modules only. The sandbox has no DNS or HTTP access, a read-only root filesystem, a writable 64 MB /tmp, 256 MB of memory, 0.5 CPU cores, and a 10-second execution limit.

Setup and configuration

Create a Cinch API key, then add the server to an MCP client. Claude Desktop and Cursor use an MCP server entry with command set to npx, arguments -y and @cinch-codes/mcp, and CINCH_API_KEY in the environment. Claude Code can add the same process with claude mcp add. On Windows, wrap npx with cmd /c.

The required variable is CINCH_API_KEY. CINCH_TIMEOUT_MS sets the client-side timeout and defaults to 20,000 milliseconds; Cinch still caps execution at 10 seconds. CINCH_BASE_URL optionally changes the API endpoint, which defaults to https://api.cinch.codes. Node.js 18 or newer is required.

Tools and capabilities

The cinch MCP server provides one tool:

  • execute_code: runs a complete program in either Python or JavaScript. The language value defaults to Python.

Output from each stream is limited to 20,000 characters and is truncated beyond that point. Timeouts and non-zero exits are reported as tool errors, allowing the assistant to recognize failed runs. Responses for exhausted credits identify the condition and tell the assistant not to retry.

Limitations and notes

This environment is intentionally minimal. Packages cannot be installed during execution, and code that depends on third-party Python or npm modules will not work. Network-dependent programs also fail. Temporary files disappear when the run ends, and the root filesystem cannot be modified.

Windows clients may report connection failures if npx is not launched through cmd /c. If npx reports a missing npm directory, create %APPDATA%\npm and retry. When diagnosing startup problems, run the process directly with CINCH_API_KEY set; a ready message followed by silence indicates that the MCP server is waiting for a client.

Read the full README View source on GitHub

Reviews

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Frequently Asked Questions about Cinch

cinch is an MCP server that connects AI assistants to Cinch’s remote code-execution infrastructure. Its main tool, `execute_code`, runs self-contained Python or JavaScript programs in disposable gVisor-isolated containers and returns stdout, stderr, exit code, and duration without accessing the client machine.

You do not need a separate install; configure the client to run `npx -y @cinch-codes/mcp` with `CINCH_API_KEY` set. `npx` fetches the package on first launch. Node.js 18 or newer is required, and Windows configurations must invoke it through `cmd /c`.

Set the required `CINCH_API_KEY` environment variable in the MCP server entry. You can also set `CINCH_TIMEOUT_MS` for the client-side timeout or `CINCH_BASE_URL` to override the default API endpoint. Restart the MCP client after saving its configuration.

Yes, cinch works with Cursor through `.cursor/mcp.json`. Add an MCP server entry that launches `npx -y @cinch-codes/mcp`, place the API key in its `env` block, and restart Cursor.

No, the sandbox provides standard-library modules only and blocks package installation at runtime. Programs should use Python’s standard library or built-in Node.js functionality, and they cannot access the network to download dependencies.

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