[whpalmer4]

I would put it in the context most likely to be encountered. If you see Bob regularly, and there's no urgency, put it in @Bob. If you need to talk to Bob right away, put it in @Calls with a date or flag to indicate the need to act quickly. Or, if you might profitably discuss a number of things with Bob, put it in the @Bob context with the rest of them, and put an action to call Bob in the @Calls context, at which point you go down the list.

The trouble with a tagging system is that unless you are fastidious and comprehensive about your tagging, it may lull you into complacency. If you have the ability to slap half a dozen tags on an action, but you forgot the one that you searched on, those other 5 tags are just a waste of space and effort. You need to be unimaginative in tagging, and imaginative in searching :-)