Mostert (knee) signed his exclusive-rights free-agent tender Wednesday, Daniel Brown of The San Jose Mercury News reports.
A key special-teams player for the 49ers, Mostert is on the mend from an MCL injury that landed him on injured reserve 11 games into the 2017 season. While it isn't clear where he stands in his recovery, there doesn't seem to be any concern that he's at risk of missing mandatory minicamp in June, let alone training camp in late July or early August.