Is the CD player MP3 in a 2005 Toyota Avalon?

No, the 2005 Toyota Avalon did not have an MP3-capable CD player as standard. While it had a CD player, it could only play standard audio CDs, not MP3 files encoded onto a CD. To play MP3s, you'd need an aftermarket solution like a cassette adapter, an in-dash MP3 player, or a portable device connected via an auxiliary input (if the car had one, which was not standard in all trims in 2005).