Traditional PRDs struggle to describe the vast capabilities of GenAI products. Evals serve as a more effective specification, communicating desired product behavior through a set of concrete examples and expected outcomes, rather than abstract descriptions.

Before building an AI agent, product managers must first create an evaluation set and scorecard. This 'eval-driven development' approach is critical for measuring whether training is improving the model and aligning its progress with the product vision. Without it, you cannot objectively demonstrate progress.

Building non-deterministic AI products fundamentally changes the PM role. Instead of creating detailed, rigid specifications, the PM's primary task becomes defining and codifying "what good looks like." This is done by repeatedly grading AI outputs to train evaluation systems and guide the model's behavior.

Evals transform product specs from ambiguous documents into testable, measurable criteria. This gives product managers more leverage and provides clear targets for engineers, improving alignment and the quality of the final product.

At Anthropic, the primary artifact for product managers is no longer the PRD. Instead, they create "evals" (evaluation sets) from user feedback to define problems and measure model improvements. This makes user needs directly actionable for AI researchers, changing a core PM workflow.

The primary bottleneck in improving AI is no longer data or compute, but the creation of 'evals'—tests that measure a model's capabilities. These evals act as product requirement documents (PRDs) for researchers, defining what success looks like and guiding the training process.

Because PMs deeply understand the customer's job, needs, and alternatives, they are the only ones qualified to write the evaluation criteria for what a successful AI output looks like. This critical task goes beyond technical metrics and is core to the PM's role in the AI era.

Instead of traditional product requirements documents, AI PMs should define success through a set of specific evaluation metrics. Engineers then work to improve the system's performance against these evals in a "hill climbing" process, making the evals the functional specification for the product.

The prompts for your "LLM as a judge" evals function as a new form of PRD. They explicitly define the desired behavior, edge cases, and quality standards for your AI agent. Unlike static PRDs, these are living documents, derived from real user data and are constantly, automatically testing if the product meets its requirements.