This is from WDWinfo.com
During dinner, gentlemen will be required to wear a dress shirt. Gentlemen wearing polo shirts, t-shirts, Tommy Bahama style shirts, etc will not be allowed admittance. Jackets and/or ties are recommended but not required. Notices will be in the Personal Navigator, on the Palo reservation card and a sign outside the elevators on deck 10 will contain this dress advisory. The Resort Casual dress code for brunch remains unchanged.
I wore Capris and a nice top. They will ask you to change if you show up wearing jeans.