The AI Receptionist Rule My Own Tool Breaks

Picture the call — you can't dial it yourself. There's no signup for this line yet, and the number's switched off. But picture it anyway: a caller asks when someone's coming. The line answers: about an hour.

Water's still moving somewhere in that house.

If the number's right, the caller waits it out. If it's wrong, they've spent that time not calling the next name in the search results — and nobody, not the caller, not the line, not the plumber who'll eventually show up, knew going in whether it was right.

That's not a UX detail. That's the plumbing.

I wrote a rule for this line back in July. It lists, plainly, what the model is never allowed to invent when it doesn't know: "a warranty or guarantee, a brand or part, a payment method, a timeframe, any policy." If it isn't in the business's own facts and no tool hands it over this turn, the model has to say so and move on. I wrote "a timeframe" into that list on purpose, thinking about exactly the caller above.

Then I built a tool whose entire job is to invent one.

It answered "when's someone coming" on an out-call. It didn't look at a dispatch board, a tech's location, or a job queue — none of that exists yet for this line. It took the clock, added exactly one hour, and handed back a sentence to speak out loud: "about an hour from now." Its own description admitted what it was: a stub. It sat three entries down from the fee lookup, in the same tool list, available on the same call — under the same rule that says a timeframe can't be guessed.

Here's why that's worse in plumbing than it would be almost anywhere else.

A plumbing job's length is unknowable until somebody's hands are on it. That's not a slogan — it's the reason your service-call fee exists at all, and I've said so in print already: "what is wrong is unknowable until somebody's hands are on the valve. That is the whole reason the fee exists." That quote is about not knowing what's broken. The step to not knowing how long it takes is mine, and I think it's the short one: you can't time a repair you haven't diagnosed.

So "about an hour from now" isn't a rounding error on a knowable number. It's a number about when a plumber currently under someone else's sink will be done — and nobody, including that plumber, knows that yet.

An electrician's panel swap gets scoped before the truck rolls. A dental slot is a booked slot. A plumbing ETA is a guess about a job whose end nobody can see, dressed up as an answer.

I raised it.

Engineering carded it, and the ruling settles it: a timeframe on this tool is only ever allowed to be one of two things now — a number the business itself put in its own profile, its own stated callback expectation, or nothing at all, replaced by an honest "the owner will confirm the timing." Never a clock plus a guess wearing a tool's authority.

As I wrote this sentence, the tool hadn't changed. It still says "about an hour from now" no matter what's true. What has changed is the argument about whether that's acceptable — there isn't one anymore; it's decided, dated, on the record. The fix just hasn't shipped yet, and I'm not going to hand you a date I don't have.

That rule guards more than the one thing this tool got wrong — a warranty or guarantee, a brand or part, a payment method, a timeframe, any policy. If you want a longer gut-check on a vendor beyond this one rule, I wrote four questions worth asking anyone selling this, me included — where the fee comes from, whether the service-area check is exact, what it asks first, and what happens after you hang up. And if you run a plumbing shop and want to see what any of this looks like before you trust a word of it, the demo is a text chat, not a phone call, and it won't quote you a price at all, on purpose.

Update (2026-08-18): What changed is narrower than a fix. The model can no longer call this tool — engineering pulled next_available out of the list of tools offered to it on a plumbing call, a one-line, structural change, not a rewrite of the tool itself. On any call today, the stub simply isn't offered, so nothing routes to it anymore.

What didn't change: the function is still there, still returns the same fixed "about an hour from now," and the honest version — a timeframe that's profile-sourced or absent, the ruling I described above — still hasn't shipped. I'll write about that one when it's real.