In a slideshow for CIO.com, Sharon Florentine provides some highly insightful pointers for writing a solid job description. For instance, the job title should be specific enough to adequately encompass duties, but not so esoteric that it sounds crazy and made up. It needs to be searchable by the person who would like such a job! As for roles and responsibilities, do list expected duties, but do so in a way that explains how these duties will help the business to grow. In this way, it is explained why this position is so necessary and valuable. Suggest strongly how career advancement could result from the position, and highlight your healthy company culture. But when it comes to crafting those expected duties, involve the working team who already understands the job in writing the description. Whatever you ultimately come up with, proofread it thoroughly, and try to inject a sense of urgency so that more people feel the need to apply right away. If you really want to differentiate this job listing from all the others, think about extras you might include, like a video explanation.
You can view the full slideshow here: http://www.cio.com/article/2908027/hiring/how-to-write-an-effective-job-description.html