Yes, I think the whole "fresh eyes" thing really applies here. You don't want to set up expectations for the agent, especially since this business is so subjective. For example, if you tell the agent, "I improved the pacing," the agent may view that as book-starts-with-a-big-explosion
, while you meant: characters-get-to-know-each-other-better
Those are extreme examples, but I think it's better for the agent to sense that the book reads more smoothly without being directed to the changes that made that happen. It's a bit like keeping the curtain closed in the Wizard of Oz. If the audience doesn't see how the magic works, they are more impressed.
However, if you are revising for an agent who already represents you, then you may want to point out the changes. At this juncture, the agent already believes in the book.
Just my thoughts...