Jones has been managing knee and oblique injuries, while Jennings has been recovering from ankle and rib issues. Their availability gives the 49ers' offense a much-needed boost as they look to improve on their 4-1 record.
Schefter also provided updates on two key players who won't suit up against Tampa Bay. Quarterback Brock Purdy (toe) has "a chance" to return in Week 7 against the Atlanta Falcons. Wide receiver Ricky Pearsall, sidelined with a knee injury, could also make his return in that same game.
With Jones set to start, rookie Adrian Martinez will serve as San Francisco's backup quarterback against the Buccaneers.
Other 49ers players listed as questionable include defensive tackles Alfred Collins (knee) and Kalia Davis (hand), safety Malik Mustapha (knee), and cornerback Upton Stout (ankle). Their official game statuses will be confirmed 90 minutes before kickoff when the team releases its list of inactive players.