Before claiming a job, you should review all the instructions to make sure you are comfortable claiming the job. If you don't understand what the client wants, it is usually best to simply avoid the job. Another writer might be more familiar with the topic and better able to understand what the client is looking for.
You can also claim the job and then ask the client to clarify. On the document message board, you can mark your message as a question. This puts the job on hold until the client responds. Again, it's worth considering first whether you should just leave the job for someone else. However, if there seems to be key information missing and other writers will probably also be wondering how to fulfill the job, it makes perfect sense to claim the job and then ask the client for more info.
