There are different aspects to Autumn given in this poem, but I would say overall that Autumn is portrayed as a generous and mellow (not too busy or driven or stressed out) woman.
In the first stanza, we see Autumn working with the sun to create all the fruits and vegetables that will feed the people (and even flowers for the bees) through the winter.
In the second stanza (as it gets later in the Autumn) we see the mellowness of her personality. She can be seen lying out in the fields, falling asleep at times.
In Keats' poem 'To Autumn' the season is personified in terms of being a friend a 'close-bosomed' friend of the sun. This means that,if these entities were human, the relationship would be that of a very close and intimate one - between two friends who were on hugging terms. Perhaps they would even cling closely together as they walked and talked. The season is warm, creative and productive - suggesting generosity and happy cheerful disposition. The friendship would be close enough for the two to devise schemes and little plots together for fun, such as how best to decorate the house vines with fruit. Autumn is depicted as being positive and constructive in its fun however - all the tricks are generous and productive (putting apples on the tree,making the gourds and hazelnuts bigger etc) Keats tells Autumn not be jealous of Spring, for he has his beauty too and it is bounteous - even though the gathering of the swallows signifies the coming of winter.