Metrics layer

A metrics layer is the place where a company defines its core metrics once, so a number like revenue or active users is calculated the same way everywhere. It is closely related to the semantic layer and often part of it.

Without a metrics layer, every report rebuilds the same logic and the numbers drift apart. With one, the definition lives in a single place and everything downstream uses it.

Why an agent needs it

An analytics agent that lacks defined metrics has to infer what you mean, and it will sometimes infer wrong. A metrics layer hands the agent the real definition, so it computes the number your company actually uses. This is a core part of context engineering.