I can't see any reason for property docstrings to be readonly:

    >>> p = property(doc='basic')
    >>> p.__doc__
    'basic'
    >>> p.__doc__ = 'extended'
    Traceback (most recent call last):
      File "<pyshell#46>", line 1, in <module>
        p.__doc__ = 'extended'
    AttributeError: readonly attribute

Among other things, making it writeable would simplify the ability to update the docstrings produced by namedtuple;

    Time.mtime.__doc__ = 'modification time'
    Score.max = 'all time cumulative high score for a single season'