I would ask your human resources department first. Most companies do have a format they want you to follow.
If you really have no guidelines, one you may want to consider is what was called start-stop-continue at a place I worked.
Begin with "continue" - what he does well and what you want him to continue doing.
Go on to "stop" - if there is anything the person has been doing that shouldn't continue.
Then "start" - areas for future development.
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