Learn Russian: Инженеры работают хорошими инструментами.

In Russian, when you do an action using an object as a tool, you just put that object in the Instrumental case. You do not use the preposition с (with). You only use с + Instrumental when you mean "together with" a person or thing (like working with a colleague). Since the tools are the physical instruments being used to do the work, the Instrumental case ending on инструментами is all you need.

How do we form the Instrumental plural for the noun инструмент?

Most plural nouns take the ending -ами (or -ями for soft words) in the Instrumental case. Since инструмент is a regular masculine noun ending in a hard consonant, we just add -ами to the end to get инструментами.

Why does the adjective хорошими end in -ими instead of the standard -ыми?

This happens because of a very important spelling rule. After the letters г, к, х, ж, ч, ш, щ, you can never write the letter ы. You must replace it with и. Because the root of this adjective ends in ш (хорош-), the normal Instrumental plural ending -ыми changes to -ими.

What is the dictionary (Nominative) form of хорошими инструментами?