GoToDeclaration

The tokens aren't that smart, as they are simply ranges of text constructed by text patterns. It is the AST model (in the Document.SemanticParseData) that you'd want to examine. You'd need to recurse down to the caret's offset and determine if there is a variable reference there. If so then you'd have to navigate the AST to look for a type/member/variable declaration in a reachable scope of that same name. Then jump to its declaration offset. There is not an easier way to do it at this time. It's something we'll consider improving support for in the future though.