This trope is all about creatures (humanoid or otherwise) who are denoted as "people" by their use of accessories such as tools, regardless of the characters being otherwise nude.
A pet animal might commonly wear a collar, but would not normally wear a coin pouch, tools, a weapon or a timepiece. Accessories of that kind would normally be a clear indication of "personhood" for the wearer, regardless of the character being otherwise nude.
The heroic space explorer is on an alien planet which seems to at least be able to sustain life as we know it. Perhaps the explorer is a scientist examining a soil sample outside her space tent. Suddenly there's a noise and the explorer looks up to behold one of the weird native lifeforms staring at her from the edge of the clearing.
"I wonder what that animal wants?" thinks the explorer. Then she realises: The creature, although otherwise nude, is wearing a belt holding a small sack, a hammer and a dagger!
The heroic space explorer is about to make First Contact!
If the character uses the accessories for their intended purpose, this would be an even more decisive indicator that the character is a person and not an animal.
This is a subtrope of Funny Animal but this trope occurs when the being is initially presumed to be non-sapient by both protagonists and audience and the being's sapience is revealed by its artifacts.
Compare Let's Meet the Meat.
- The Far Side had one comic with a bipedal cow standing behind a table, showing off a bunch of lumpy stone objects. The caption just read, "Cow tools."
In a Far Side retrospective book, Gary Larson said this particular strip got him more inquiries than any other in his career, from people wondering what the heck the comic was supposed to be about. The answer is that Larson recalled the topic of tool use from an anthropology course, and the fact that real-life apes use tools, and that got him thinking: "Ape tools are rather primitive in comparison to human tools. If cows used tools, how primitive would those be?"
- In Lilo & Stitch, Stitch is mistaken for a dog after he loses his laser guns (despite having six limbs) and then Lilo later realizes that Stitch is intelligent when he does things like riding a bike and building elaborate models of San Francisco.
- Chewbacca of the Star Wars franchise wears a bandolier over his shoulder and handles various repair tools and weapons, which helps visually affirm that he's a technology-using alien and not some sort of bipedal beast in spite of his only vocal sounds being grunts, growls and roars.
- Averted in The Cat from Outer Space (1978). An alien that looks like a cat is stranded on Earth. His super-computer/communication device looks like a glowing cat collar, so he is mistaken for a common house cat.
- In the Honor Harrington universe, the Treecats of Sphinx (small, six-limbed arboreals) were originally thought to be nonsentient. It began to dawn on the human colonists that they were wrong when they were seen to use stone-age tools (chipped stone hand-axes and woven nets).
- In Alice in Wonderland, the main story begins when Alice sees a rabbit with a pocketwatch and waistcoat and follows to investigate.
- A. Bertram Chandler's "The Cage": Survivors from a crashed starship (on a planet where clothes don't survive due to some aggressive fungus) are captured by aliens and put in a zoo. Attempts to convince the aliens they are sentient by making baskets or demonstrating mathematics fail. But when they build a cage and put an alien mouse into it... well, only sentient beings are bastards enough for that.
- In the Little Fuzzy novels, the first indication that the Fuzzies were sentient was their use of sharpened sticks to kill invertebrate prey.
- One of the countless hominids on Ringworld was a borderline-sentient species which, while unable to use fire in their aquatic habitat, did use flaked stone tools (a borderline example since it is never stated whether or not the species wears clothes).
- In Tarnsman of Gor, Tarl meets a Nar, a member of the Spider People, who wears only a Universal Translator strapped to his thorax.
- Inverted in David Brin's Uplift series when humans are considered inferior to whales and dolphins because we are unable to do things without using tools.
- In Anne McCaffrey's Decision at Doona, human settlers on a new world encounter a village of intelligent cats. Both species assume the other is pre-sentient due to the primitive living conditions in each other's colonies. The aliens decide the humans are intelligent based on a child's ability to play games.
- In L. Neil Smith's Confederacy novels, there is an uplifted coyote named G. Howell Nuahuatl (the G. stands for Greenriver). He wears a vocoder collar, synced to the impulses in his cybernetically augmented brain, and a custom motile collar equipped with twin guns and ear pads to protect his hearing. In later stories, he uses a backpack that has a cybernetically-controlled hand.
- Discussed in Janet Kagan's Hellspark, in which a survey team are trying to figure out if the local birdlike aliens, which have never been seen using tools, are sapient. The protagonist points out that on some planets she's visited, the surveyors themselves might not necessarily be recognised as sapient tool-users because the nature of their tools would not be apparent — for instance, an observer might note that they don't build fires for warmth, not knowing that their clothes have integrated heating elements. This turns out to be the case with the birdlike aliens, which have a highly advanced technology they control by means not apparent to the survey team.
- In the fantasy trilogy The Balanced Sword, one of the main characters is an Intelligent Toad who doesn't wear clothes but does wear a sword belt and a pack with his equipment in. Both are actually spelled to prevent people noticing them if he doesn't want them to, because in his line of work there are times when it's useful for people to not realize he's sapient.
- The so-called Beagles in The Long Earth series are basically a race of Wolf Men. Because they're furry, they don't need clothing, and because they lack opposable thumbs, they have a limited ability to use tools, but they still wear belts containing basic implements and weapons.
- Doctor Who: In the Fifth Doctor story "Kinda", the titular beings are initially thought to be non-sentient—but the human scientist points out that their necklaces look remarkably like DNA double-helices.
- In Kamen Rider Gaim, one of the story's many Nothing Is the Same Anymore moments is triggered by the appearance of a blurry photo that seems to depict an Invess carrying a sword. Dr. Sengoku immediately has all records of the photo erased while he conducts his own investigation, fearing that if the Invess have "Overlords" smart enough to negotiate with humans, then this could ruin his plans to use their invasion for his own benefit.
- Conventional paleoanthropology divides prehistoric hominins between "pre-human" australopithecines and the early members of Homo, the "human genus" by the employment of stone tools, although since skeletons of both have been found in association with stone tools, it's rather up in the air if australopithecines used tools too. Even prior to modern anthrolopogy, philosophers like Augustine of Hippo said, when speculating on the possible existence of other beings, that if they wore clothes, used tools, domesticated animals etc. this would show they were sapient and (for Augustine) possessed souls.
- Subverted in the case of crows. Crows are known tool inventors and users. Some crows using human cars and traffic lights as nut crackers, others known to bend wire into shapes to help them access otherwise unreachable food. This has not translated to humanity considering them sapient.
- One of the most reliable indicators of sapience is skeletons with evidence of healed fractures, specifically fractures that have healed well enough to suggest they were assisted in some way by outside medical care. Aside from putting paid to the Social Darwinist pet theory that caring for the "unproductive" is a recent phenomenon, this would be evidence of the complex, abstract problem-solving skills needed to realise the value of setting and splinting a broken bone.