These pages were originally at
http://www.randomly.org/projects/MCCP/, which doesn't seem to exist anymore. This copy was rescued from the Wayback Machine. Modifications and cleanup has been made since that date: the protocol description itself is untouched.
Zugg software has a mirror of an older version (from abandoned.org) here. I've created a local mirror of that mirror here.
AFKMud has an additional mirror here which it appears they update somewhat often. Looks like AFKMud has gone the way of the dead domain.
No effort has been made to check or update any of the links in the attached pages: the purpose of this mirror is just to save the protocol documentation.
These pages describe a protocol that can be used by mud servers to transparently compress their output to their clients, based around the use of zlib and telnet option negotiation. It can greatly reduce the outgoing bandwidth needed by the mud server, and decrease client latency.
And yes, the protocol is MCCP with two C's, not MCP which is something completely different.