Joseph was claimed off waivers by the Giants on Tuesday, Kerry Crowley of The San Jose Mercury News reports.
Joseph was designated for assignment by the Athletics on Sunday, but he'll join San Francisco's 40-man roster just a few days later. According to manager Bruce Bochey, Joseph will see time at third base when Evan Longoria needs an off day, per John Shea of the San Francisco Chronicle. Pablo Sandoval (elbow) was placed on the 60-day injured list to clear a roster spot.