For AX 2012 R2/R3, Visual Studio 2010/2013 Data Tools would be the tool to peek into the existing cubes, you can open the AOT >Visual Studio Projects > Analysis Services Projects > Dynamics AX to see the details about the Measures and Dimensions. I am not sure about AX 2009, though.
Kewn, thank you for answer. Our users use Exel to make reports with data from OLAP cubes. I want to write a document(user manual) for them. The document have to describe the details about the Measures and Dimensions. The Measures and Dimensions is changing very rapidly. Our users have no permission to open AOT and Visual Studio but they want to peek into the existing cubes. I have trouble with the document for them. Do you use any tools to write OLAP documentation? or where can i find a good example of OLAP cube documentation?