The objective of a cover letter is to identify and explain its contents. It will provide the reader a record of the items and documents sent.
As such it should be specific and brief. If you are sending multiple pieces of information, a bulleted list will effectively highlight the contents of your package.
In the sample cover letter, the writer indicates that the contents are in response to a request received in a meeting. The scope of her letter is extremely brief, as both parties are aware of the pertinent background information.