First the brief is provided by the client that is brought into the company by the client servicing personnel.定语从句
First the brief is provided by the client 主句,主系表结构,被动语态
that is brought into the company by the client servicing personnel.定语从句,修饰先行词client.
首先,信息是由客户提供的,那个客户由客户服务人员带进公司的.