No finish you can apply to a metal surface (especially tools) is going to last forever. And while stainless steel tools would be more rust and corrosion resistant than plaint metal or painted metal, without any care, and exposure to salt, even stainless steel with rust corrode.

I think the solution that would last the longest, would be stainless steel tools, that are occasionally wiped with a rust preventative chemical/oil. Less expenssive stainless tools are available, but it seems like they don;t last long (the producing companies that is) on the market. There was a import tool company by the name of Nikota a fewer years ago that offered a product line that included reasonably priced air powered, battery powered, ac powered, and handtools of a very nice quality. The handtools were made in Asia, stainless steel (not-chromed), and came with a lifetime warranty). For a short time (a period of a few years) it looked like they might make it (marketing looked good and they were being sold by quite a few retailers).

Ultimately the company failed. I think Big Lots (PicNSave) did much of the liquidation. I got a set of the stainless steel combination wrenches (box or open on one end and ratcheting wrench on the other end), that are some of the nicest tools I own, regardless of the brand, and they have held up nicely. I still have some of the Nikota air tools as well and they are holding up well for what I use them for. Sears sells some stainless handtools (not Craftsman brand, and selected, not complete sets) and I'd recommend trying them for replacement tools.