Why AI agents need a dry run before you pay for real execution

Every agent run has two phases, and only one of them costs real money. The first phase is the contract: the goal, the checks, the boundaries. The second is execution: the swarm, the sandbox, the model calls. Most teams skip straight to phase two and pay for the mistakes that were already in the contract.

Failure is usually decided before the run starts

A vague goal does not fail halfway through. It fails at the end, when the agent reports SUCCESS on a contract that never said what you meant. A missing boundary does not cause a crash. It causes a quiet detour into refactoring. The expensive part is not the tool calls. It is discovering, after minutes and dollars, that the words were wrong.

What a dry run catches

• Uncheckable criteria. If nobody can grade a check, the run cannot verify anything.
• Vague goals. Activity phrasing that lets the agent pick its own definition of done.
• Missing boundaries. No non-goals means the agent is free to drift.
• Vacuous passes. Checks the agent can satisfy without doing the job.

The math is insultingly one-sided

A dry run costs a dollar and takes seconds. A real multi-agent run starts at ten dollars, takes minutes, burns model quota, and occupies a sandbox. If the contract is broken, the dry run tells you in one line: "this check is uncheckable" or "this goal describes activity, not an outcome." Then you fix the form and run again for another dollar.

The alternative is paying for a full run on a contract nobody checked, then debugging a confident report about the wrong thing. That is how agent work earns its reputation.

Dry runs are not a guarantee

Honest caveat: a clean dry run does not mean the real run will succeed. The world is messy, sandboxes have surprises, and long tasks accumulate drift. What a dry run buys you is a much higher floor. The contract problems, the most common and most expensive class of failure, are gone before a single expensive call.

When to skip the dry run

If the job is trivial, the contract is already sharp, and a failed run costs nothing, skip it. For everything else, the $1 audit is the cheapest insurance in the workflow.

Run the $1 audit on your next work order, or start from a template that already has the checks written.