The last thing they said. I'll never have to say "What?" 4 times in a row again.

Number of times they molested kids.

First name.

"Hey Janine, can you move your cart out of the way, thanks, gonna get by here and go get some ice cream sandwiches."

"Excuse me, Ravi, trying to get off the train, one moment, thanks."

"Oh hey, you're a Tanis too, just like me, neat!"

This will absolutely weird everyone out.

Realtime running count of lies told

How likely they are to have sex with me this very second behind those bushes over there.

Good God I'm shallow sometimes...

Is "how much I would like them on a scale from 0 to 10 (with a resolution of like 0.01) if I got to know them at a deep level" allowed? Or is that cheating?

I'm here to toot for the "lifetime farts" number

all the others seem a lot more invasive, so I'll go with their pronouns/gender so I never have to ask and be awkward

% of how genuine they are with me, easy to figure out who's worth the time and who isn't.

Could be a problem in a relationship tho. I take it back, just the cumulative numbers of fart in a lifetime.

Some kind of "empathy score." Not sure what the formula would be, but it would reflect how readily they feel empathy for another person, and how many other people they can care about.

A narcissist would have a 0 -- they can only care about themself. Someone with very limited empathy would have a small number -- say, they can only care about their immediate family, and they need to really get to know someone before they care about that person. People who naturally care about others, even if they don't know the other person, would have high numbers.

This number would sometimes just flat out tell you that certain people should be avoided, or certain conversations are pointless with that person. Or if you do need to try to convince them of something, the number may show you how to frame the conversation. E.g., show how it's in their own interest if they have a low number.

The time and date of their death.

A scale of 1-10 at how likely we could be friends.

Healthbar.

"Hey, fuck you! I'm gonna kick your ass, man!"

"Mighty big talk for someone who only has 4hp."

An icon to indicate if they washed their hands after the last time they used the bathroom.

A boolean indicating if they want a conversation or not

Number of cumulative years they would be imprisoned for, had they been caught and convicted of every single crime they ever committed.

I'm betting most adults are not at zero.

Human or Not Human

How willing they are to talk to you right now. You can always pick the right person to talk to if you need to ask a question, give a friend the exact amount of space they need if they’re going thru something, and easily identify people that are interested in you (or not). Best of all, though, you can spot someone who’s a little too eager to talk and avoid a hostage-style conversation where they won’t let you leave politely

None. Someday, some company will build and sell a tool that actually does that, and it will be hella privacy invasive. Actually, it'll probably just be another invasive feature added to the Ray Ban perv glasses.

HP bar, level, and whether they have aggro

Number of racial slurs used genuinely.

A percentage of how much our core values/morals/beliefs align, weighted by how important they are to us.

It would make it super easy to know upfront who I should include in my life and who I shouldnt.

Total net worth. No hidden assets or secret bank accounts. Every last cent that a person is worth. Also, it gets brighter/more noticeable whenever you're advocating for something that increases your net worth.

I feel like this would be the only way to get a lot of people to connect the dots.

Number of times they've lied

A sort of hunger bar. It would be useful in so many situations.

Similar to some other answers here, but "number of times they've deliberately lied". Not only do you get an instant "trustworthiness" stat, you also get to know if they're lying to you right now.

Quality of Life impact: How much damage (or benefit) their actions (work, lifestyle, whatever) have done for the net quality of life across the globe. I figure anyone who drives to work is probably doing a little more harm than good, but perhaps they make up for it by being a good school teacher or something, whereas AI coders might make things worse ... but mostly I'd like to see if ANY world leaders score in the positive.

Just a simple binary 0 or 1 to indicate whether the person means what they said literally or figuratively.

I don't really care to invade people's privacy, even for altruistic-seeming reasons. I just need a hint about how to interpret a person every so often.

horny%

Times they told the truth.

If it's objective truth, sweet! Motherload I can asking anyone the a question to the secrets of the universe and know whether they're wild guess was true!

If it's subjective truth, also useful, but you know just lies or ignorance detector