The Brendel signing was already known and first reported on Friday by Tom Pelissero of NFL Network.
Barrett and Jones-Smith were among the three former practice squad members who were not re-signed by the 49ers on February 4. The other was defensive lineman Ray Smith.
Barrett (6-2, 250) entered the NFL after signing with the Detroit Lions as an undrafted rookie free agent on May 12, 2017. He appeared in two games that season and registered one tackle and a sack before being waived by the team on September 20, 2017, and then signed to the practice squad two days later.
Barrett was signed by the Oakland Raiders on April 6, 2019, and waived on September 3, 2019. The 49ers initially signed him to the practice squad on November 27, 2019.
Jones-Smith (6-7, 345) originally entered the NFL after signing with the Houston Texans as an undrafted free agent on May 11, 2018. He was waived by the Texans on September 1, 2018. Jones-Smith signed with the Miami Dolphins on April 9, 2019, and was waived by the team on August 31, 2019.
The 49ers initially signed Jones-Smith to the practice squad on October 1, 2019.