"Written in small cursive script" 或 "Written in small, flowing handwriting"(后者更侧重于描述流畅的草写风格,不严格局限于传统“草书”概念,可根据具体语境选用)。若强调传统书法中的“草书”且字较小,可表述为 "Written in small cursive (Chinese) characters"。