Engineering brief

Brains vs. hands: how to build production-safe AI agents

AI Engineer3 min read · saves 14 min

At a glance

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Warnings
  • Vendor pitch

The most dangerous mistake in production agents is letting an LLM execute its own plan. The harness must be deterministic.

Separating planning from execution prevents LLM errors from escalating into production incidents.

Watch if you are choosing an agent harness framework for production SRE or operations.

Summary

The core claim. The speaker argues that production-ready AI agents require a strict separation between planning and execution. The plan is the non-deterministic output of an LLM. The execution is a deterministic, durable workflow that should never leave room for hallucination. He calls this the brains vs. hands distinction.

Why the analogy matters. The speaker draws a direct parallel to microservices architecture. Just as you would not deploy a single microservice that does everything, you should not deploy a single agent that reasons, plans, and acts autonomously. Instead, a harness (the hands) should own all execution, and the LLM (the brains) should only plan what needs to happen next.

The specific failure mode. Without this separation, a critical action like a production cluster restart could be made by an LLM without a human gate. The speaker gives the example of a harness that ensures every cluster restart follows the exact same deterministic steps. He argues that leaving approval gates to an LLM introduces unacceptable risk.

The operational requirement. The harness must be durable and long-running. It has to survive network failures, partition events, and infrastructure restarts. Durability, he says, is table stakes, not a feature. The harness must also be idempotent where possible, and when it is not, it must record side effects so they can be handled separately.

The technical implementation. The speaker demonstrates a Conductor-based harness that ingests an LLM's multi-step plan and compiles it into a deterministic workflow. The demo shows an SRE remediation loop that runs twice: first to diagnose and roll back, then to verify recovery. The harness decides not to roll back on the second iteration because it was already done.

What this means for teams. The talk is framed as an engineering strategy, not a product pitch, though Conductor is the underlying tool. The insight is that production agents should be treated as late-bound sagas: a finite set of deterministic tools that an LLM can compose at runtime. Teams looking to run agents in production should focus on the harness architecture first, not the model.

My take

I agree with the brains vs. hands framing, but I would push back on how novel it is. We have been building sagas and state machines for years. The LLM just becomes another input source. What concerns me more is that the demo here is too polished. Real failures happen when the plan is incomplete or contradictory, not when a tool call is missing. Teams should test their harness against bad plans, not just happy-path demos. And I would add that building a deterministic harness on top of an LLM that can produce infinite variations of plans is a combinatorial explosion problem. The speaker mentions late-bound sagas but does not address how to validate all possible paths.

What to do with this

  1. Define the deterministic harness boundary for every agent in production.
  2. Add a human approval gate for any action that could cause data loss or downtime.
  3. Test each harness against at least three failure scenarios: incomplete plan, contradictory plan, and plan with missing tools.

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