This is probably "Hunting Rights" by P.M. Fergusson and G.L. Robson. The major issue with this identification is that it was only published in Analog, May 1988. But the rest matches, especially the bit at the end when the alien is deciding how to modify a third limb into a hand.
The intelligent alien hunter watches a spaceship land:
Not that H'Tash was an animal; a pure predator he was: death and hunger packed into a massive, razor taloned, blunt faced hunter. He lacked the hands, tentacles or other manipulating organs which technological sentients use to build their civilizations, but he was far from being an animal. H'Tash thought and analyzed, and knew there were odd looking creatures inside that dark cigar shape, creatures which could be dangerous.
Instead of having a body with three pairs of legs like a typical hexapod, H'Tash has 3 forelimbs and 3 hind limbs:
H'Tash squatted on his three powerful hind legs and stretched his forelegs against a buttress root. He purred in idle good humor and, with a muscular ripple of this three-meter-long body, scarred eighteen, four-centimeter deep furrows in the root.
H'Tash isn't exactly fascinated by the explorers, but recognizes them as a potential danger that needs to be investigated:
H'Tash knew of only one sure way to get that knowledge, by finding,
killing and eating one or more of the aliens. Knowledge lived in the flesh, therefore to its source he must go. H'Tash began to plan, very carefully.
And once H'Tash has all the knowledge he can gather he starts to plan further ahead:
Like the Federation bureaucrats, H'Tash dozed and dreamed, but more effectively. He had watched the aliens at work. Yes, he thought, a manipulating hand would be a great advantage. His mind wandered over the possibilities: not the outer hunting claws, definitely not. How would one catch and kill food without them? But the central paw... Shorten the claws, extend the joints, reversing one, possibly two digits, to give opposition. Combine that with a few minor modifications of the already prehensile tails... Deep within H'Tash's body, tiny organisms, the same organisms who had made him immune to the tranquilizing agents of the collectors began to make other, more gradual changes in his genetic code.
The issue's cover image is for "Hunting Rights" and depicts H'Tash as something like an alien wolf.