Every web site I found had the same info:
France:
Cafes and restaurants include a 15% service charge in the bill, as required by French law for tax assessment. Service compris indicates that the tip has been added to the bill, but sometimes the wait staff do not receive any of it.[26] Tipping is better received in venues accustomed to tourists, but can be treated with disdain in smaller food establishments and those in more rural areas. The amount of the tip is also critical. A 5% tip will do nicely for good service. For superior service in higher-end eating establishments, a more generous tip would not be out of place.[27] However, the rare waiter/waitress accustomed to more generous foreign customers have no problem receiving a tip of up to 10% or more.

web page