Compare 14 semantic layer tools for BI and AI agents: dbt, Cube, AtScale, Looker, Snowflake, Databricks and more, with pricing and MCP support.

A data dictionary documents every table and column: meaning, type, allowed values, keys. See a full example, a template, and SQL to generate one.

What a context layer is, how it differs from a semantic layer, and how to build one for data agents, with OpenAI's six-layer architecture as the example.

Data ontology, explained with one example built four ways: taxonomy, ontology, knowledge graph, semantic layer. Plus how Palantir's Ontology works.

A semantic model maps raw tables to business meaning: entities, metrics, joins. See how Power BI, dbt, Snowflake, and AI agents each define one.

The harness is the software around a language model that decides what the model sees, which tools it can call and what it remembers, and for a data agent it matters as much as the model itself.