Former England Test captain Alastair Cook is available for Essex's three opening County Championship games of the season.
Former New Zealand captain Brendon McCullum will rejoin Middlesex for nine 2017 T20 Blast group matches.
England batsman Nick Compton extends his contract with county champions Middlesex until the end of the 2018 season.
England pair Haseeb Hameed and Ben Duckett are named in the MCC team for March's Champion County game against Middlesex.
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How to get into cricket - physical exertion with a chess-like element in matches which range from half an hour to five days.