When Agent's name is longer than 32 characters, it throws the error which has nothing to do with the name being too long:
U00003359 Agent 'SQL02.BLUH.I.AM.MORE.THAN.32....' uses an incorrect Company Key.
32 characters is the limit for the agent name as it is stated in the documentation, however, the incorrect error message is a defect.
Release : SQL Agent 12.1.0+build.852 and 12.1.1+build.936
Component : SQL Agent.
Please upgrade to one of the following versions:
Automation.Engine 12.3.1 - pending release in October 2019
Automation.Engine 12.4.0 - pending release in March 2020
Workaround: shorten the agent name to less than 32 characters.