Think of the essay as similar to the "persuasive essays" you wrote in high school or college. The point is to support a thesis. The essays will be graded primarily on the quality of their argument. So, for example, if your argument is structurally invalid, so that the conclusion does not follow from the premises, this will count against it. Also, if the argument leans heavily on a contentious premise, for which you do not provide any particular support, this will count against it.  That being said, I am realistic about how little support can really be provided in a brief essay. Your writing will be judged by a standard appropriate for such an essay. Necessarily, your argument must rest on a number of assumptions, for which you do not argue, due to lack of space. Your essay can be greatly strengthened by calling explicit attention to these assumptions. Argue for your most contentious premise/s. Your less contentious premises or background assumptions can be assumed, but again, please point these out.  Intimately related to the quality of the argument, is the clarity of your writing, on which the paper will also be judged. If you are using a word in a somewhat unique way, please define that term.  Finally, grammar and proper citation matter too. Cite using the Chicago/Turabian method.  As to the content, there are two concerns you want to balance in your writing. On one hand, engaging with a text is a chance to show your close reading skills, which can make an essay substantially more impressive. On the other hand, you want to avoid summarizing your reading, like a book report. Your aim is to give an argument, but to do so in conversation with whatever authors you are reading.