In our LS documentation, many fields are of the string type, but the documentation does not mention the format and semantics of these strings in many cases.

Most important examples:

• Expression update contains type: string[], but what is the type? Is it a list of qualified names of intersection types? Can the element contain anything besides a qualified name? What happens with union types? Can it contain generic types?
• Suggestion Entry has returnType: string, which is also not clear.

But I would like to see no string types at all and replace them with type aliases with well-defined semantics.

Knowing type constraints will allow us to write more robust code on the IDE side, and defining additional type aliases for the current LS protocol will also help design future LS APIs.