Windows Command Line MCP Server

Instructions

Implementation Reference

• index.ts:56-100 (handler)

  The asynchronous handler function for the 'list_running_processes' tool. It constructs platform-specific commands (PowerShell Get-Process on Windows with optional filter, ps aux | grep on Unix) , executes via executeCommand helper, and returns the stdout as text content or error.

    async ({ filter }) => {
      try {
        let cmd;
        
        if (isWindows) {
          cmd = "powershell.exe -Command \"Get-Process";
          
          if (filter) {
            // Add filter if provided
            cmd += ` | Where-Object { $_.ProcessName -like '*${filter}*' }`;
          }
          
          cmd += " | Select-Object Id, ProcessName, CPU, WorkingSet, Description | Format-Table -AutoSize | Out-String\"";
        } else {
          // Fallback for Unix systems
          cmd = "ps aux";
          
          if (filter) {
            cmd += ` | grep -i ${filter}`;
          }
        }
        
        const stdout = executeCommand(cmd);
        
        return {
          content: [
            {
              type: "text",
              text: stdout.toString(),
            },
          ],
        };
      } catch (error) {
        return {
          isError: true,
          content: [
            {
              type: "text",
              text: `Error listing processes: ${error}`,
            },
          ],
        };
      }
    }
  );

• index.ts:53-55 (schema)

  Zod input schema defining the optional 'filter' parameter as a string for matching process names.

  {
    filter: z.string().optional().describe("Optional filter string to match against process names"),
  },

• index.ts:49-52 (registration)

  Registration of the 'list_running_processes' tool using server.tool(), including name and description.

  // Register the list_running_processes tool
  server.tool(
    "list_running_processes",
    "List all running processes on the system. Can be filtered by providing an optional filter string that will match against process names.",

• index.ts:17-47 (helper)

  Platform-aware helper function 'executeCommand' that runs commands via execSync, with modifications for non-Windows environments to strip Windows-specific prefixes.

  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()}`);
      }
    }
  }