This is an OPS-DIR review of PKINIT Algorithm Agility (draft-ietf-kitten-pkinit-alg-agility). This ID updates PKINIT following the guidelines in BCP 201 to make it algorithm agile and to expose acceptable algorithms. This is a very well written clear document. I do not find any operational issues with the document except that the document could use a section on interoperability (old server-new client, new server-old client). There are a few words about the topic deep in section 6 about the supportedKDFs field but I do not see a general discussion or a discussion about the kdf field. The text about the supportedKDFs field could be moved to a new section and each of the old/new combinations could be addressed. I see this as an operational issue because compatibility issues are a frequent source of operational headaches.