PowerShell Exec MCP Server

Instructions

Args:
    properties: List of ComputerInfo properties to retrieve (optional)
    timeout: Command timeout in seconds (1-300, default 60)

Implementation Reference

• src/server.py:78-90 (handler)

  The core handler function for the 'get_system_info' tool. It constructs a PowerShell 'Get-ComputerInfo' command, optionally filters by specified properties, ensures JSON output formatting, and executes it via the shared execute_powershell helper.

  @mcp.tool()
  async def get_system_info(properties: Optional[List[str]] = None, timeout: Optional[int] = 60) -> str:
      """Get system information.
      
      Args:
          properties: List of ComputerInfo properties to retrieve (optional)
          timeout: Command timeout in seconds (1-300, default 60)
      """
      code = "Get-ComputerInfo"
      if properties:
          properties_str = ",".join(properties)
          code = f"{code} -Property {properties_str}"
      return await execute_powershell(format_json_output(code), timeout)

• src/server.py:850-909 (helper)

  Shared utility function that securely executes arbitrary PowerShell code with timeout protection, dangerous command validation, and optional MCP context logging. Called by get_system_info to run the system info query.

  async def execute_powershell(code: str, timeout: Optional[int] = 60, ctx: Optional[Context] = None) -> str:
      """Execute PowerShell commands securely.
      
      Args:
          code: PowerShell code to execute
          timeout: Command timeout in seconds (1-300, default 60)
          ctx: MCP context for logging and progress reporting
      
      Returns:
          Command output as string
      """
      # Validate timeout
      if not isinstance(timeout, int) or timeout < 1 or timeout > 300:
          raise ValueError("timeout must be between 1 and 300 seconds")
          
      # Validate code
      if not validate_powershell_code(code):
          raise ValueError("PowerShell code contains potentially dangerous commands")
  
      if ctx:
          await ctx.info("Validating PowerShell code...")
  
      # Create and run process
      if ctx:
          await ctx.info("Starting PowerShell process...")
      
      process = await asyncio.create_subprocess_exec(
          "powershell",
          "-NoProfile",      # Don't load profiles
          "-NonInteractive", # No interactive prompts
          "-Command",
          code,
          stdout=subprocess.PIPE,
          stderr=subprocess.PIPE
      )
  
      try:
          if ctx:
              await ctx.info("Executing command...")
          stdout, stderr = await asyncio.wait_for(
              process.communicate(),
              timeout=timeout
          )
      except asyncio.TimeoutError:
          process.kill()
          if ctx:
              await ctx.error(f"Command timed out after {timeout} seconds")
          raise TimeoutError(f"Command timed out after {timeout} seconds")
  
      if process.returncode != 0:
          error_msg = stderr.decode() if stderr else "Command failed with no error output"
          if ctx:
              await ctx.error(f"PowerShell command failed: {error_msg}")
          raise RuntimeError(error_msg)
      
      result = stdout.decode() if stdout else ""
      if ctx:
          await ctx.info(f"Command completed successfully, returned {len(result)} characters")
          
      return result

• src/server.py:30-34 (helper)

  Helper function that appends '| ConvertTo-Json' to PowerShell code if missing, ensuring JSON-formatted output. Used by get_system_info before execution.

  def format_json_output(code: str) -> str:
      """Add JSON formatting to PowerShell code if not present."""
      if not code.strip().lower().endswith('| convertto-json'):
          code = f"{code} | ConvertTo-Json"
      return code