on Writers Helping Writers:

A writer once told me they’d created their query list specifically to avoid agents who asked writers for a synopsis because writing one was harder than getting a whole novel reader-ready. I laughed at the time, but since then I’ve encountered a lot of fear and trepidation about writing a synopsis, especially as the move toward Query Manager has made asking for a synopsis common practice. But the synopsis is a powerful tool to assess story structure via the convergence of plot arc and character arc, so creating one that is accurate not only makes your pitch package stronger, but it can help you better understand your story and know when it’s truly ready for readers.