No. No, no.
This is NOT a good turn of phrase for the Savvy Querier.
Your book isn't forthcoming until it's been sold. If you're looking for an agent, we HOPE the book will sell, but it's not on any publication schedule, thus not "forthcoming"
Unless you mean it's forthcoming from your printer, in which case, you better write the thing before you query.
And "require an agent" Well, yes, sure, I think having an agent is a good idea but saying you require one sounds as though you think the only thing you need to do is announce you need one.
Am I the first to tell you that is not the case? Well, sorry for the bad news, but there it is.
This is not artful or courteous or gallant language. It's pretentious and does not serve you well. There's a lot to be said for just telling me what your book is about.