Activate Sarcatog by sacrificing Sword of the Meek.
Skittering Precursor triggers, creating a 0/1 Eldrazi Spawn creature token.
When the Eldrazi Spawn enters the battlefield as a 1/1 due to Street Riot, Sword of the Meek triggers, returning Sword of the Meek from your graveyard to the battlefield attached to the Eldrazi Spawn.
Resolve the Sarcatog ability, giving it +1/+1 until end of turn.