Theory:

     GRANDFATHER bought Toto from a tonga-driver for the sum of five rupees. The tonga-driver used to keep the little red monkey tied to a feeding-trough, and the monkey looked so out of place there that Grandfather decided he would add the little fellow to his private zoo.
 
     Toto was a pretty monkey. His bright eyes sparkled with mischief beneath deep-set eyebrows, and his teeth, which were a pearly white, were very often displayed in a smile that frightened the life out of elderly Anglo-lndian ladies. But his hands looked dried-up as though they had been pickled in the sun for many years. Yet his fingers were quick and wicked; and his tail, while adding to his good looks (Grandfather believed a tail would add to anyone’s good looks), also served as a third hand. He could use it to hang from a branch; and it was capable of scooping up any delicacy that might be out of reach of his hands.
Explanation:
 
Ruskin Bond is the author of the story. He explains in this story how his grandfather's habit of upbringing animals had once landed him in trouble. Since the narrator's grandfather was interested in buying a monkey, he bought it from a tonga-driver; and it cost around five rupees. The tonga-driver had not allowed the monkey freely but tied it around the feeding trough. It made the monkey feel so uncomfortable. When Grandfather had bought the monkey, he decided to put it into his private zoo.
 
The writer or the narrator hints here that his grandfather had his private zoo, reflecting his passion for animals or birds.
Toto was the name of a monkey, and it looked so pretty. As the narrator's grandfather was interested in upbringing the animals or birds, he might have bought Toto. His mischievous eyes twinkled under deep-set brows. His pearl-like white teeth and his deep smile looked frightening enough to scare elderly Anglo-Indian ladies.
 
Toto’s scary smile.jpg
Toto’s scary smile
 
Though Toto looked pretty with gleaming eyes and a scary smile, the narrator says Toto's hands seemed too dry, like being pickled on the sun for years together. Still, the narrator admires Toto's hands and tail.
The narrator also points out that his grandfather always prefers supporting a tail linking to one's good look. Moreover, the tail can also be like a third hand to help. The narrator's grandfather also believed that it could hang from a branch; pick up any delicious fruit or food items that could not reach through Toto's hands.
 
Meaning of difficult words:
  
S.No.
Words
Meaning
1.
Tonga
A two-wheeler carriage used in rural areas 
2.
Trough
A long narrow open container used for holding animals food
3.
Wicked Slightly cruel but intending to upset anyone
4.
Beneath Under or below something
5.
Sparkle To shine brightly
6.
Delicacy Something pleasant to eat
7.
ScoopTo pick up
Reference:
National Council of Educational Research and Training (2006). Moments. The Adventures of Toto – Ruskin Bond (pp. 7-10). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.