I am using the jenkins-cli.jar file from my jenkins server, and each time it starts, it asks for my ssh key passphrase. I would like it to use my ssh keychain, so I don't need to enter it on every call.
If that matters, on OSX I use the default setting for keys, I don't have a manually configured ssh-agent right now.
The Jenkins CLI client does not support SSH agents.
As a workaround, you can generate a dedicated key without a passphrase, associate it with your Jenkins account, and instruct the client to use this key on every call.