勉强 + [verb phrase]
勉强 + [person]
[noun] + 很 + 勉强
勉强 before a verb most often means "barely, only just": the result was reached, with nothing to spare.
It pairs naturally with 能, 够 and potential complements like 搬得动 "can lift".
勉强 also says someone did a thing without wanting to. The verb is usually one of agreeing, accepting or smiling.
As a verb, 勉强 takes a person: make someone do what they don't want to. It is mostly negative or advice.
As an adjective, 勉强 describes a reason, an argument or a smile that doesn't hold up.
勉强 never means trying hard in a good sense. For effort, use 努力.