So…it’s not just a question of emailing these agents and saying ‘will you represent me?’ First of all, you need to check on their websites, or their web page if they are part of an agency, and understand what they are requesting.
Bio? Book blurb…or perhaps the full synopsis? 1 chapter or 3 or 3000 words? What is important is to give the agent exactly what he or she is asking for. Obviously one also need to provide a cover letter.