The fact that you use the word "Just" before "networking tool" is disconcerting.
You can learn everything taught in an MBA program on khan academy or YouTube. You're there for the connections, the network, the character-building, and the experience. 6 Months out, you think I remember how to price a bond? Hellll no.
Clubs are an important part of establishing yourself as social, outgoing, and amicable. I missed out on one important club at INSEAD (Rugby), and kicked myself later. I eventually joined and found that the social opportunities I had been missing were highly valuable ones.
There are academic/professional clubs (Consulting Club, Africa Club, Entrepreneurship Club) and leisure clubs (Rugby, Extreme Sports) - You'd be wise to join at least one of each.
My #1 recommendation for business school: learn how to speed-read, super-learn, and retain information.