Most of the moderator tools are not secret, and they're discussed openly here on meta. But there are a few that are not public and that should remain secret, specifically all the tools that are related to detecting sock puppets and vote fraud. Then there are some borderline cases like the new moderator view for user profiles, it's not exactly secret, but any discussion of it is likely to involve some details on how moderators find vote fraud or socks, which is not something we want to reveal.
The consequence of this is that feedback from moderators on these tools and support requests are handled entirely in private, mostly by mail and the Teacher's lounge chat room. Chat works for quick feedback, but it's rather awkward for more comprehensive stuff. Whenever such tools are discussed, I miss the option to just make a meta post instead of scattering the discussion in chat. Mail can work for longer feedback, but then you miss out on the comments from other moderators. Searching in chat is also not at all comparable to searching for a post on meta, looking up any old discussions is very tedious if not almost impossible at times.
What I propose is a place where we can discuss the secret tools like we do for the non-secret tools on meta. I'm intentionally a bit vague on the technical details, this might be a private SE instance or something else entirely. It would be solely for support and feature requests about the moderator tools that cannot be revealed in public.
I know that a similar request for a Moderators SE site was denied in the past, but my proposal is intentionally restricted to avoid the potential issues the old proposals had. The only valid topic are the secret moderator tools, anything that can be discussed in public would be off-topic. It's also not meant for guidance on specific situations, e.g. how should I deal with this user. These restrictions should address the concerns that were voice by SE about the older versions of this idea.