MCP Filesystem Server

Instructions

Args:
    paths: List of file paths to read
    encoding: File encoding (default: utf-8)
    ctx: MCP context

Returns:
    Dictionary mapping file paths to contents or error messages

Implementation Reference

• mcp_filesystem/server.py:113-142 (handler)

  MCP tool registration and handler for 'read_multiple_files'. This is the entry point decorated with @mcp.tool(), which receives parameters, calls the core operations method, formats exceptions for JSON compatibility, and returns the results.

  @mcp.tool()
  async def read_multiple_files(
      paths: List[str], ctx: Context, encoding: str = "utf-8"
  ) -> Dict[str, str]:
      """Read multiple files at once.
  
      Args:
          paths: List of file paths to read
          encoding: File encoding (default: utf-8)
          ctx: MCP context
  
      Returns:
          Dictionary mapping file paths to contents or error messages
      """
      try:
          components = get_components()
          results = await components["operations"].read_multiple_files(paths, encoding)
  
          # Convert exceptions to strings for JSON serialization
          formatted_results = {}
          for path, result in results.items():
              if isinstance(result, Exception):
                  formatted_results[path] = f"Error: {str(result)}"
              else:
                  formatted_results[path] = result
  
          return formatted_results
      except Exception as e:
          return {"error": str(e)}

• mcp_filesystem/operations.py:206-237 (handler)

  Core implementation of read_multiple_files in FileOperations class. Validates paths, reads file contents asynchronously, catches exceptions per file, and returns a dictionary of path to content or exception.

  async def read_multiple_files(
      self, paths: List[Union[str, Path]], encoding: str = "utf-8"
  ) -> Dict[str, Union[str, Exception]]:
      """Read multiple files at once.
  
      Args:
          paths: List of file paths
          encoding: Text encoding (default: utf-8)
  
      Returns:
          Dictionary mapping file paths to contents or exceptions
      """
      # Explicitly type-annotate the results to help mypy
      results: Dict[str, Union[str, Exception]] = {}
  
      for path in paths:
          try:
              abs_path, allowed = await self.validator.validate_path(path)
              if not allowed:
                  # Create an error and store it
                  error_msg = f"Path outside allowed directories: {path}"
                  results[str(path)] = ValueError(error_msg)
                  continue
  
              content = await anyio.to_thread.run_sync(
                  partial(abs_path.read_text, encoding=encoding)
              )
              results[str(path)] = content
          except Exception as e:
              results[str(path)] = e
  
      return results