The key features of successful essays in the UPSC examination include clarity, coherence, and depth. A well-structured essay should have a strong introduction that lays out the thesis, followed by logically organized paragraphs that develop arguments with relevant examples. Clarity of thought is essential, as complex issues must be articulated simply yet effectively. Incorporating diverse perspectives and critical analysis enriches the content, while a concise conclusion reinforces the main arguments. Furthermore, maintaining a formal and objective tone throughout the essay enhances its professionalism, making it more appealing to evaluators.