Source: vba.asn.au 
The title is part of a well known bridge saying:
[box type=”info”]If God gives you Spades bid something.[/box]
Spades is the Boss Suit because it outranks the other suits in the bidding. You are more likely to be able to outbid the opponents to get to a makeable contract or an effective sacrifice.
All this means you should strain to to get a Spade suit onto the table.
A very important part of this is making an overcall when you can, especially when you have limited values.
Given all of this what should East do over 1 and why?
What East should do is to bid 1. Bidding a major at the 1-Level is something you should strive to do to get into the auction.
With the current hand 1 is clear after which West will certainly compete to 5 which should at least ensure E/W get a decent score.
Because of the 2 voids you can make 13 tricks but it is very unlikely anyone could bid slam knowing what they are doing.
At the table, failing to bid 1 meant that E/W allowed N/S to play in 4. Not a good result.
Are there any guidelines about what is a minimum overcall?
There is a reasonable guideline you can use when in doubt.
Make a small card in one of your plain suits an Ace. If the resulting hand is a clear opening bid you should overcall.
If it is a marginal opening bid then think about it. Now things like the quality of the suit and vulnerability make a difference.
Here, making the 2 the A passes the test easily so we have an Overcall. This is only a rough guide but it gives you a starting point.
it also makes it less likely you will score +100 in the future when you can make 13 tricks in Spades.