What is adjective for mouse size?

There isn't a single perfect adjective for "mouse size". Here are some options, depending on what you want to convey:

General Size:

* Tiny

* Small

* Miniature

* Petite

* Compact

Comparison to Mouse Size:

* Mouse-sized

* The size of a mouse

Specific Size:

* Pocket-sized (if it's small enough to fit in a pocket)

* Hand-sized (if it's roughly the size of a hand)

The best choice will depend on the context. For example, if you're describing a small object, "tiny" or "miniature" might be appropriate. If you're comparing something to the size of a mouse, "mouse-sized" would be a good choice.