* Agitation: This is the most common noun form and refers to the act of stirring up or disturbing something, or the state of being disturbed or excited.
* Agitator: This noun refers to a person who stirs up others to action or protest.
For example:
* The news of the disaster caused widespread agitation. (Here, "agitation" refers to the state of being disturbed.)
* The union leader was a skilled agitator, able to mobilize workers for strikes. (Here, "agitator" refers to the person who stirs up action.)
Therefore, the best noun form for "agitate" depends on the meaning you want to convey.