About js-sandbox MCP Server
js-sandbox MCP Server provides an isolated environment for executing JavaScript code. It is intended for MCP clients that need code execution with configurable time and memory limits.
Key features
- 01Isolated JavaScript execution
- 02Configurable execution timeout
- 03Configurable memory limit
- 04Execution result returned
Use cases
- 01Run JavaScript snippets from an MCP client
- 02Limit execution time for code tasks
- 03Constrain memory used during execution
MCP support
The server exposes an `execute_js` tool that runs supplied JavaScript code and returns the result, with optional timeout and memory limits.
Configuration
Local server config is the same for every client. Copy it into your client’s MCP config file.
We haven’t collected a package or remote endpoint for this server. Follow the instructions in the project README.
Tools
Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.
Details
From the project README
js-sandbox MCP Server
A Model Context Protocol server that provides a secure JavaScript execution environment.
Features
Tools
execute_js- Executes JavaScript code in an isolated environment- Parameters:
code(required): JavaScript code to executetimeout(optional): Maximum execution time in milliseconds (100-30000ms)memory(optional): Memory limit in bytes (1MB-100MB)
- Returns the result of code execution
- Parameters:
Security
- Isolated code execution in a controlled environment
- Configurable execution time and memory limits
- Protection against malicious code
Development
Install dependencies:
npm install
Build the server:
npm run build
Development mode with auto-rebuild:
npm run watch
Installation
Installing via Smithery
To install JavaScript Sandbox Server for Claude Desktop automatically via Smithery:
npx -y @smithery/cli install @garc33/js-sandbox-mcp-server --client claude
To use with Claude Desktop, add the server configuration:
MacOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%/Claude/claude_desktop_config.json
{
"mcpServers": {
"js-sandbox": {
"command": "/path/to/js-sandbox/build/index.js"
}
}
}
Debugging
Since MCP servers communicate over stdio, debugging can be challenging. We recommend using MCP Inspector, which is available as:
npm run inspector
The Inspector will provide a URL to access debugging tools in your browser.
Comments
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