Is your tour hotel Londres Eiffel? If so, your closest Metro Stop is Ecole Militaire on Line 8 and it is awkward to get to the RER line B to CDG from there. The route will require 2 Metro changes.
Here's one of the routes:
Ecole Militaire in the direction of Balard 1 stop to the station called La Motte-Picquet Grenelle. Transfer there to Line 6 in the direction of Nation. Take that to the Denfert-Rochereau stop and transfer to the RER B for the airport. I "think" you have to watch for the train labeled CDG.
There may be an easier route and if so someone will suggest it.
I'm saying this to say that a cab is going to be way easier than 2 changes on the Metro up and down stairs and escalators with luggage. As indicated, I'd want a cab pick up for 4-5 hours ahead of my flight and indeed, that is what I do when I leave from this neighborhood. Your hotel front desk can arrange your cab the night before and tell you if you need more time for that in case of some kind of local disruption.
IF you are at Londres Eiffel, you can certainly go out for a last walk to the Eiffel Tower from your hotel, lol!! I'm an early bird, so I'd eat at 7 then hoof it over to the ET for a half hour walk and then finish up things at the hotel for a taxi pick up.
Have a wonderful time!