(partial notes based on Sri Vishvapriya Tirtha's lecture on Mahabharata-Tatparya-Nirnaya. Compiled by Sri Omkar Deshpande on dvaitadotorg)
The Mahabharata Tatparya Nirnaya has 32 chapters. The figure is 32, not 31, not 33. Srimad AnandatIrtha is described as having 32 daihika-laxaNas (such as a specific height, proportionate eyes, ears, etc) and so he has indicated that by having 32 chapters in the text. The first chapter summarises the decisive purport of the Vedas as establishing the Lord's supremacy. The second chapter contains the decisive purport of the Mahabharata. The third chapter discusses the creation and destruction of the universe. Chapters 4-9 explain the Ramayana. Chapter 10 describes the avatAra of VedavyAsa. From chapter 11 onwards, AchArya explains the meaning of the Mahabharata as well as events in the BhAgavata.
MadhvAchArya authored all of his works through mental inspiration (mAnasika-preraNA) from VyAsa. But as far as the Mahabharata-Tatparya-Nirnaya is concerned, VyAsa personally instructed him to write the correct meaning of the Mahabharata when MadhvAchArya met VyAsa face-to-face at Badari. Thus, this grantha is due to both mental inspiration as well as direct instruction from VyAsa.
Narayana Panditacharya has called the MBTN as the nectar of the MBH. In the Mahabharata, there are several episodes that can throw us into a state of confusion. It is a huge text and was authored a long time ago. As it was passed from one mouth to another, there were interpolations and changes that happened. MadhvAchArya himself says that people in his time are
removing what they don't want, and adding whatever they want. The entire foundational vision with which VyAsa had authored the Mahabharata was getting shaken up. Sections that talked about the glories of the Lord were being pulled out. So VyAsa instructed Madhvacharya to give the real purport of Mahabharata to the society, containing the original intent with which He had composed it. The result was this grantha.
naahaM karta hariH karta