MercuryOS reminds me of the Apple Lisa - The way it managed applications invisibly was a step in the direction of selecting tools based on intentions. It was a document-centric system, which MercuryOS isn't, but a step in the same direction.

For some time, Windows 95 (IIRC) had a Templates folder. You'd put documents in it and you could right-click a folder and select New->Invoice or something similar based on what you had in the Templates folder. It was similar to Lisa's Stationery metaphor.