As the sibling notes, that would usually be marked as Generated-By or Generator or similar tags. Claude is only using "Co-Authored-By" for the same reason that

As the sibling notes, that would usually be marked as Generated-By or Generator or similar tags. Claude is only using "Co-Authored-By" for the same reason that Anthropic is calling claude "he", not "it": to anthropomorphize the machine in the public's perception.