You cannot read contents of a PDF file with TestComplete without any external tools since PDF is a closed format. However, there are several ways to read data from a PDF file opened in Adobe Acrobat Reader in TestComplete. For example, you can use the MSAA plug-in to get the text or use the OCR plug-in.
Please refer to the "Testing With Microsoft Active Accessibility" help topic to learn how to use the MSAA plug-in. For information on the OCR plug-in, see the "Optical Character Recognition - Overview" help topic.