Who makes a decision to intentionally walk a batter?

Question

Say there are men on second and third with one out. So the pitcher intentionally walks a batter to load the bases and set up a possible double play. Maybe the pitcher didn't want to pitch to a good batter anyway.

Who makes the decision for an intentional walk? Does the pitcher make this decision on his own? Or is it somehow communicated to him by a manager or a coach? Or is it true that a pitcher makes this decision some of the time, but the manager or coach can order him to walk a particularly dangerous batter, or pitch to a certain, presumably weak, one?

Answer 1

According to Wikipedia:

The intentional base on balls is often referred to as a "four-fingered salute." This reference stems from the manager's holding up four fingers to signal an intentional walk to the pitcher or catcher. It is a "salute" to the batter that the manager admits to wanting to pitch to someone else instead.

which seems to suggest that in earlier times, it was usually the manager who made this decision. This information from the same article suggests it's still the case today:

Prior to the 2017 season, as part of Major League Baseball's efforts to improve the pace of play, the rules were amended to allow a manager to order an intentional walk by simply signaling the umpire.

This does not mean the pitcher can never make this decision on his own (I simply do not know enough about MLB to answer that part.)