Now in early access

Turn vibes into confidence

Find out how your AI agent fails, then improve it on quality, latency, and cost

Vibes

#agent-updates

sarah · 9:14 AM

We shipped the new model yesterday. How's it looking?

marco · 9:31 AM

Feels better? I tried a few prompts and chatted with it, not sure tbh 🤷

sarah · 9:36 AM

Okay, let's keep a close eye on customer support tickets for the next week in case we need to roll back

marco · 9:41 AM

👍 I'll skim some transcripts tomorrow and flag anything that looks off. No idea how many is enough though

Confidence

#agent-updates

marco · 9:02 AM

We shipped the new model yesterday, everything looking good. So far bookings have increased 4.2% with 90% confidence.

marco · 9:04 AM

p50 latency is down 38%, tail latency slightly elevated — will look into it. Overall cost is down 24%.

Booking rateP(beats control)
gpt-5.6-terra medium44.7%97%Likely better
sonnet-5 medium · control42.9%Baseline

+4.2% vs control · 90% credible interval

“You changed the agent. Did it actually get better?”For most teams, the honest answer is still: we don't know.
The question

You don't know which scenarios matter

You have an idea, but nobody has counted which ones carry the most traffic, which fail most, or which touch revenue.

You can't tell if a change actually helped

You swap in the latest model, but how does it perform on your use case? What happened to quality, latency, and cost?

Your data sits there doing nothing

Every request you've served is training data for a model of your own. Most teams keep renting.

Understand

Your failures, grouped, named, and ranked

Your traffic comes in and your failures come out grouped and ranked. No eval suite to build, no dataset to label, nothing to maintain.
Scenarios · from your traffic

Book a room

48% of traffic · 2.1% fail

Change an existing booking

27% of traffic · 6.8% fail

Cancel and refund

14% of traffic · 11.4% fail

Compare properties

11% of traffic · 3.9% fail

Failure modes · ranked
Promised a refund policy that doesn't exist31%
412 sessions
Quoted the wrong cancellation window24%
319 sessions
Confident answers to unanswerable questions17%
226 sessions
Dropped context after a booking change11%
146 sessions

Every scenario, mapped

Core scenarios and edge cases pulled from your own traffic, ordered by volume, failure rate, and business impact.

Surprises get caught

The same groupings across production, offline, and live, so a fix that creates a new problem is caught early.

No evals to maintain

One AI judge scores every session, and those scores are correlated with the quality metrics you already report.

Experiment

Find the best AI configuration for your use case

Every candidate is graded by an AI judge and measured against the metrics your business already reports. Statistical confidence across quality, latency, and cost.

Live experiment · Hotel bookings completed

VariantP(beats control)
your-slm-v1winner73.3%
100%Likely better
terra · prompt v472.1%
100%Likely better
sonnet-5 (control)68.4%
Baseline

Each bar shows the 50% and 90% credible interval around that variant's booking rate, against the control line at 68.4%.

your-slm-v1 vs control
+0.0%
bookings
0%
p50 latency
0%
cost / 1K

Failure clusters

vs control
877 → 722−18%

failures across these clusters

nonexistent_refund_policy_promised−24%

412315 sessions

wrong_cancellation_window_quoted−28%

319231 sessions

dropped_booking_context+4%

146152 sessions

unnecessary_human_handoffNew

024 sessions

Experiments you can run in an afternoon

Candidate prompts, models, and configs run against requests you have already served. Quick to set up, and nothing reaches a user.

A verdict on your own metric

Bookings, resolutions, merged PRs, whatever you already report, with an AI judge scoring every session alongside it.

A failure-mode diff, every time

Which clusters improved, which got worse, and if any new clusters emerged.

Specialized models

Your data is your moat

Your production traffic and your experts' assessments become a specialized language model built for your use case — better, faster, and cheaper than the frontier model it replaces. No ML team required.

Better →← Cheaper
Custom model
your-slm-v1
In production today
Existing closed and open models

Find your Pareto frontier across closed and open models — or break it entirely with a custom model tailored to your use case

Beats the frontier where it counts

A general model has to be good at everything. Yours only has to be good at one thing: your specific task.

The dataset builds itself

Your production traffic is filtered and curated into training data automatically.

Your experts' judgment compounds

Every grade and explanation your team provides is signal the model learns from.

Integration

One prompt away

Keep the AI SDK you already use. Swap the base URL, add two headers, and actionable insights start flowing.

Agent onboarding prompt

Read three.dev/agents.md and perform the setup to send this project's traffic through three.dev.
View agents.md ↗

Ship on evidence, not vibes

Your next agent change deserves better than “LGTM, ship it.”