That's much like promising you a salary of 200k ... in some undisclosed unit of currency. The rational valuation of it is roughly nil, even if they succeed. So you have to decide if you'd still take the position if that part of the compensation weren't offered at all.
If you are being paid market rate, there is no reason for you to know the % of equity offered until you bring the company to an important stage. But if you are discounting your salary for equity, then it should be in writing.
Well, they must give you the exercise price; and if you assume it is a fair price (or 15% discounted, which is often the case) of $x/share, you know that e.g. if the company grows up 10 times in value, you get a bonus of $n<i>x</i>(10-1) where n is the number of shares you get an option for. So in that sense, the total outstanding is not interesting.<p>It is interesting in the sense that you need to know the total company valuation to have an idea of how much the company can still increase its value. If an unknown facebook competitor "mugshotbook.com" is already valued at $5B without any users, it is unlikely your option will be worth anything ever, regardless of how much you are getting.<p>DO NOT FORGET: Options are a contract to buy in the future at a price known today. They are not equivalent to shares (if they were, you'd be taxed for the face value on the day of the grant!). If the value does not go up, they are worth exactly nothing. If you get facebook options with exercise price reflecting $50B market capitalization, and facebook IPOs at $50.5B when you are vested, what you earn is 1% of the share value of your options (because of the exercise price), not a penny more! In numbers: If you get $10M worth of facebook options today, and facebook IPOs at $50.5B, you get a $100K bonus for your (e.g.) 4 years of vesting, or $25K/year -- not shabby, but a far cry from the $10M you think you'll be owning.