An analysis should provide all needed information and clear description what have to be done.
You have to:

• list the requirements for creating analysis for tasks. An analysis should contain:
  • brief overview of the task
  • what have to be done
  • example how to be done
  • overview of the whole task but strict analysis of the current revision
  • other requirements...
• analysis should be done at least one sprint before
• the analysis have to be made by one developer and one QA
• notice what the results of an analysis are
• make analysis template and give at least two examples of good analysis
• point where to keep the analysis (wiki page with the task and the current revision for example)