You Do Need power plug adapter while traveling from Tonga to Lebanon.

Here is Why You Need An Adapter

The outlet and plug type used in Lebanon are C, D and G and in Tonga is I. This is how they look like.

Tonga

In Tonga, outlets of type I are in use.

Type I

Lebanon

In Lebanon, outlets of type C, D and G are in use.

Type C

Type D

Type G