The Google style guide contains an excellent Python style guide. It includes conventions for readable docstring syntax that offers better guidance than PEP-257. For example:
"""Calculate the square root of a number.
n: the number to get the square root of.
the square root of n.
TypeError: if n is not a number.
ValueError: if n is negative.
I like to extend this to also include type information in the arguments, as described in this Sphinx documentation tutorial. For example:
def add_value(self, value):
"""Add a new value.
value (str): the value to add.