What are the costs and attorney's fees awarded to a plaintiff on a special motion to strike?

"If the court finds that [the] special motion to strike is frivolous or is solely intended to cause unnecessary delay, the court shall award costs and reasonable attorney's fees to a plaintiff prevailing on the motion, pursuant to Section 128.5." ( 425.16, subd. (c)(1); see 128.5, subd. (a) [permitting court to order party "to pay the reasonable expenses, including attorney's fees, incurred by another party as a result of actions or tactics, made in bad faith, that are frivolous or solely intended to cause unnecessary delay"].) This provision is designed to "discourage[ ] [the filing of] unmeritorious strike motions." (Ketchum v. Moses (2001) 24 Cal.4th 1122, 1137.)