Decoder. plain-English AI glossary

Agent Evaluation

▲ Rising

Measuring whether an agent actually completes real tasks, not just whether the model sounds smart.

Think of it like

A road test, not a written exam — it doesn’t matter what the driver can recite if they can’t park the car.

Example

You run the agent against 200 recorded support tickets and score how many it resolved end-to-end without a human stepping in.

How it actually works

Evaluating agents is harder than evaluating a single answer because success is a whole trajectory — many steps, tool calls, and side effects — and there’s often more than one right path. You care about task completion, cost, and safety, not just whether the final text looks good. The messy truth is that reliable agent evals are still an open problem, and a lot of reported numbers are fragile.

For product teams

A demo proves an agent can work once; evaluation tells you how often it works — insist on the second.

For engineers

Score full trajectories on task success, cost, and safety across a fixed benchmark of scenarios.

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