I see thanks. Good question!
Visual studio is correctly showing the tip. The problem is that arduino have not defined the names in the prototypes.I just looked at other hardware such as esp8266 and it has the names defined.
If you click on pinMode then press F12 you will see the definition in the arduino.h which is installed with the arduino ide.
void pinMode(uint8_t, uint8_t);
Esp8266 has this in its arduino.h
void pinMode(uint8_t pin, uint8_t mode);
To be fair to arduino there are a number of manufacturers that haven;t defined the names and it might be that they have a long history when adding names to prototypes wasn't allowed. (I'm not sure if that's true or not)
You can also right click and "Peek Definition" if that's easier than F12 (goto definition).
Having said all that I have found a problem that I will look into. If you click "vMicro>Toggle Hidden Files" shortcuts to the arduino core are added to the current project. If you end up with lots of folders in the root then close and reopen the project (okay to save changes) and the view will refresh properly. You will see all the arduino source in the \src folder.
You will get a lot of intellisense errors which I will look into but pressing F12 on pinmode will then show the pinMode method instead of the prototype. If intellisense errors annoy set the filter on the errors list to "open documents"
Click "vMicro>Toggle Hidden Files" again to remove the links to the arduino core (or delete manually). they do not harm if they exist in a project.