The Eiffel VS Code extension supports Go to Type Definition, allowing you to quickly navigate to the class that defines the type of an Eiffel symbol.
Place the cursor on a function or attribute name, then:
The Editor opens the base class of the type associated with the selected feature.

Instead of navigating away from the current file, you can use Peek Type Definition:
The corresponding class is displayed in an inline popup, allowing you to inspect the type definition without leaving the current context.

Go to Type Definition and Peek Type Definition are available for all major Eiffel symbols that have a type, including:
Result and Current entitiesPrecursor in feature redefinitionsTrue and False