Filesystem MCP Server

Instructions

Implementation Reference

• main.py:285-317 (handler)

  The handler function for the 'read_text_file' MCP tool. It resolves the file path using _resolve, checks if it's a text file with _is_text, reads the content, applies optional line range slicing, and returns the content or an error message.

  @mcp.tool
  def read_text_file(
      path: str, fromLine: int | None = None, toLine: int | None = None
  ) -> str:
      """Read the contents of a UTF-8 text file, optionally within a line range.
  
      Args:
          path (str): File path to read (absolute or relative to allowed directories)
          fromLine (int, optional): Starting line number (1-indexed, inclusive)
          toLine (int, optional): Ending line number (1-indexed, inclusive)
  
      Returns:
          str: File contents as text, or error message if failed
  
      Note:
          - Path must be within allowed directory roots
          - Only reads UTF-8 text files (binary files will return error)
          - If line range specified, returns only those lines
          - Line numbers are 1-indexed
      """
      try:
          rp = _resolve(path)
          if not _is_text(rp):
              return f"Error reading file: '{rp}' is not a UTF-8 text file or is binary"
          lines = rp.read_text(encoding="utf-8").splitlines(keepends=False)
          if fromLine is None and toLine is None:
              return "\n".join(lines)
          start = (fromLine or 1) - 1
          end = toLine or len(lines)
          return "\n".join(lines[start:end])
      except Exception as e:
          return _human_error(e, "reading file")