During his time in Madrid, James scored 36 goals in 111 appearances while winning La Liga once and two Champions League titles, as well as two UEFA Super Cups and two Club World Cups.
However, he fell out of favour under Zinedine Zidane, prompting a two-year loan to Bayern Munich with an option for the Bundesliga side to buy at the conclusion of his stay.
The 28-year-old finished with 15 goals in all competitions during his two seasons with Bayern, who opted against making his stay permanent in Bavaria this summer.
As a result, his future remains uncertain as the club season draws closer, and Mendes insists he does not fully know what Real Madrid will do with the player.
Asked about James' future, Mendes told Marca: "You'll have to ask the president (Florentino Perez) who is here next to me.
"I just want the best for the player and the best for the club."
James – who represented Colombia at the Copa America in June – scored seven league goals in each of his two seasons at Bayern.
Real Madrid have spent big this summer, having brought in the likes of Eden Hazard, Luka Jovic, Ferland Mendy, Eder Militao and Rodrygo.
However, the club are dealing with an injury issue in midfield following the recent injury to Marco Asensio.
The future of Gareth Bale also remains uncertain following Zidane's recent comments that a move could be on the cards for the Wales star.