At the unexpected party, Gandalf gives Thorin a map of the Lonely Mountain, which has information about a secret door and the key to the secret door.
Gandalf is worried that Smaug may become an ally to the newly returned Sauron.
He showed them that thorins grandfather had a pairof earings
Umm i think it was fair because gandalf told thoron that bilbo was a burgaler and hes probably the least important to thorin
The moon letters brought out additional information. Elrond found them while looking at the map with Gandalf and Thorin one evening. They provided information on the secret passage.
"There is one point that you haven't noticed," said the wizard, "and that is the secret entrance. You see that rune on the West side, and the hand pointing to it from the other runes? That marks a hidden passage to the Lower Halls." The Hobbit JRR Tolkien