Not every research paper is freely available.
Some journals publish their articles as Open Access, allowing anyone to read the complete paper. Other journals require a paid subscription or institutional access before the full paper can be viewed.
When only the abstract is publicly available, Rooted Research will clearly indicate that the report has been generated using the available abstract rather than the complete publication.
If you have access to the full paper, uploading the PDF will usually produce a more detailed and comprehensive report.