Good quick reference parameters for discrete components
WOW... that's an interesting approach. What information you add to the envelope is of course the problem, which is why you asked this question in the first place. Ultimately, what you need to add is open to opinion.

If it's a decent sized envelope you could simply cut out and stick the boilerplate specs from the sheet on the envelope..


However, ultimately, someone will need a number that's not there, and those numbers are fairly meaningless for many devices.

Why don't you do it on the computer instead. List your parts in a database with a location field so you can fetch them easily. e.g.: Cabinet number/shelf/rack/bin.. Then you can search the DB for the parts that meet your requirement rather than thumbing through envelopes. 

You could also include a link to the full data-sheet for the part in the DB. You could also consider adding vendors, vendor part numbers, and pricing.