Jev didn't make my agents smarter.
It made the boring decisions cheap enough to run at every step.
That's the unlock. Not AGI. Not "replacing Claude." A typed yes/no decision you can afford to ask 200 times in one session.
I spent the week running it in a real loop, not a demo.
The old stack:
user goal → big model thinks → picks a tool → checks if it's done → writes the next message
It works until the bill shows up, the cache dies, or the agent quietly leaves the task.
The new stack is simpler:
1. Code owns the paths.
2. Jev judges messy text.
3. The big model plans and writes.
Three questions:
• Is the goal done?
• Which tool comes next?
• Does a human need to see this?
If the answer space is known, I don't generate. I pick.
If B depends on A, I don't batch them. I only run independent questions in parallel.
If Jev says "no" to "is this done," I don't let it keep calling tools. Freeze. Restate the goal in one line. Then continue.
Cheap verification without a brake just makes drift faster.
The practical lesson was harder:
Typed and wrong still ships.
A schema doesn't make the decision correct. A 52/48 split isn't a decision. It's a handoff.
I stopped trusting the label and started trusting the cut.
High-confidence no → stop.
High-confidence yes → go.
Gray band → bigger model or me.
Also, lock the main model at session start. Let Jev raise effort or pick a specialist mid-thread. Rerouting the main model every turn kills the cache and makes you pay twice.
What I don't use Jev for:
Code.
Thread summaries.
Inventing options.
Generate the candidate list in code. DOM, retriever, tool trace. Then let Jev pick.
That's the difference between a decision model and a chatbot in a trench coat.
For people shipping MVPs, this is the part I'd test.
A lot of agent cost isn't intelligence. It's asking a frontier model to act like a switch statement.
Routing.
Done or not.
Safe or not.
Keep or drop this tool call.
Those aren't writing jobs. We just didn't have a primitive that was fast, cheap, and could return uncertainty with a number.
Jev is that primitive.
Nimble and the rest can copy the recipe. The brand won't matter in three months. The layer will.
Weekend test:
Pick one agent you already run.
Find every call that only picks something. Replace it with a typed question. Threshold on confidence, not just the answer. Put a brake on "no."
Then look at the bill and the drift.
If neither moves, you used it like a smaller chatbot.
If both move, you put the system back in your hands.