Windows Command Line MCP Server

Instructions

Implementation Reference

• index.ts:454-513 (handler)

  The primary handler logic for the 'execute_command' MCP tool. It performs security validation to block dangerous commands, sets up execution options, constructs the shell command (cmd.exe /c on Windows), calls the executeCommand helper, and returns the stdout as text content or an error.
  async ({ command, workingDir, timeout }) => { try { // Security check: Ensure only allowed commands are executed const commandLower = command.toLowerCase(); // Block potentially dangerous commands const dangerousPatterns = [ 'net user', 'net localgroup', 'netsh', 'format', 'rd /s', 'rmdir /s', 'del /f', 'reg delete', 'shutdown', 'taskkill', 'sc delete', 'bcdedit', 'cacls', 'icacls', 'takeown', 'diskpart', 'cipher /w', 'schtasks /create', 'rm -rf', 'sudo', 'chmod', 'chown', 'passwd', 'mkfs', 'dd' ]; // Check for dangerous patterns if (dangerousPatterns.some(pattern => commandLower.includes(pattern.toLowerCase()))) { return { isError: true, content: [ { type: "text", text: "Command contains potentially dangerous operations and cannot be executed.", }, ], }; } const options: any = { timeout }; if (workingDir) { options.cwd = workingDir; } let cmdToExecute; if (isWindows) { cmdToExecute = `cmd.exe /c ${command}`; } else { // For non-Windows, try to execute the command directly cmdToExecute = command; } const stdout = executeCommand(cmdToExecute, options); return { content: [ { type: "text", text: stdout.toString() || 'Command executed successfully (no output)', }, ], }; } catch (error) { return { isError: true, content: [ { type: "text", text: `Error executing command: ${error}`, }, ], }; } }
• index.ts:449-453 (schema)

  Zod input schema defining parameters for the execute_command tool: required 'command' string, optional 'workingDir' string, and optional 'timeout' number (defaults to 30000ms).
  { command: z.string().describe("The command to execute"), workingDir: z.string().optional().describe("Working directory for the command"), timeout: z.number().default(30000).describe("Timeout in milliseconds"), },
• index.ts:446-514 (registration)

  Registration of the 'execute_command' tool on the MCP server using server.tool(), including name, description, schema, and inline handler function.
  server.tool( "execute_command", "Execute a Windows command and return its output. Only commands in the allowed list can be executed. This tool should be used for running simple commands like 'dir', 'echo', etc.", { command: z.string().describe("The command to execute"), workingDir: z.string().optional().describe("Working directory for the command"), timeout: z.number().default(30000).describe("Timeout in milliseconds"), }, async ({ command, workingDir, timeout }) => { try { // Security check: Ensure only allowed commands are executed const commandLower = command.toLowerCase(); // Block potentially dangerous commands const dangerousPatterns = [ 'net user', 'net localgroup', 'netsh', 'format', 'rd /s', 'rmdir /s', 'del /f', 'reg delete', 'shutdown', 'taskkill', 'sc delete', 'bcdedit', 'cacls', 'icacls', 'takeown', 'diskpart', 'cipher /w', 'schtasks /create', 'rm -rf', 'sudo', 'chmod', 'chown', 'passwd', 'mkfs', 'dd' ]; // Check for dangerous patterns if (dangerousPatterns.some(pattern => commandLower.includes(pattern.toLowerCase()))) { return { isError: true, content: [ { type: "text", text: "Command contains potentially dangerous operations and cannot be executed.", }, ], }; } const options: any = { timeout }; if (workingDir) { options.cwd = workingDir; } let cmdToExecute; if (isWindows) { cmdToExecute = `cmd.exe /c ${command}`; } else { // For non-Windows, try to execute the command directly cmdToExecute = command; } const stdout = executeCommand(cmdToExecute, options); return { content: [ { type: "text", text: stdout.toString() || 'Command executed successfully (no output)', }, ], }; } catch (error) { return { isError: true, content: [ { type: "text", text: `Error executing command: ${error}`, }, ], }; } } );
• index.ts:17-47 (helper)

  Supporting helper function 'executeCommand' that performs the actual execSync call. Handles Windows directly, modifies commands for non-Windows compatibility by stripping Windows shell prefixes, and provides fallback error handling.
  function executeCommand(command: string, options: any = {}) { if (isWindows) { return execSync(command, options); } else { // Log warning for non-Windows environments console.error(`Warning: Running in a non-Windows environment (${platform()}). Windows commands may not work.`); // For testing purposes on non-Windows platforms try { // For Linux/MacOS, we'll strip cmd.exe and powershell.exe references let modifiedCmd = command; // Replace cmd.exe /c with empty string modifiedCmd = modifiedCmd.replace(/cmd\.exe\s+\/c\s+/i, ''); // Replace powershell.exe -Command with empty string or a compatible command modifiedCmd = modifiedCmd.replace(/powershell\.exe\s+-Command\s+("|')/i, ''); // Remove trailing quotes if we removed powershell -Command if (modifiedCmd !== command) { modifiedCmd = modifiedCmd.replace(/("|')$/, ''); } console.error(`Attempting to execute modified command: ${modifiedCmd}`); return execSync(modifiedCmd, options); } catch (error) { console.error(`Error executing modified command: ${error}`); return Buffer.from(`This tool requires a Windows environment. Current platform: ${platform()}`); } } }