The Kansas City Chiefs and other teams around the league don't announce roster additions until the player has physically put pen-to-paper and signed his contract. That's why you see someone like Kyle McCarthy tweet last week that he's joining the Chiefs and the team doesn't make it official until Tuesday night.
The Chiefs confirmed that McCarthy, the former Denver Broncos safety, has signed with the team. He spent the last two seasons in Denver before the Broncos cut him the week of their Wild Card playoff game (which is a little cold-blooded, but not as bad as Tiquan Underwood getting released the night before the Super Bowl).
Per a league source, it's a one-year deal.
McCarthy has been a special teamer for most of his career so that's likely what he'll do in KC. Romeo Crennel hired two new special teams coaches this offseason so they'll get a look at McCarthy and others in offseason workouts.
McCarthy is a former Golden Domer, coming out of Notre Dame, where he saw action in 50 games. He entered the NFL undrafted.