[mcphage]

I'm not sure this goal is very practical, even in the toy example you used (being able to swap data sources for weather forecasts).

If you can use a common vocabulary to access multiple APIs, that requires that all APIs implement the same feature set. Which means getting the API sources to agree on the features to implement, and how to describe them, and stop them from adding any features on that the others don't have. But of course, they'll all be motivated to add their own features, to distinguish themselves from their competition.

And once a API consumer is using a feature that other API producers don't support, then the consumer is locked into that producer, and the whole shared vocabulary is for naught. And of course the API consumers will be looking for additional features, because those translate into features that they can offer to their customers.

Basically, this requires API producers to work together to hobble their ability to meet their customers' needs, all to make it easier for their customers to drop them for a competing endpoint. So it looks like a net negative for everybody.