Agents

The catalog is the API — a governed mesh over MCP

The Fabric + Mesh reference ended with a promise: an MCP-exposed catalog tool that answers which sensitivity level applies to a column holding an EU IBAN, from the live LF-tag policy rather than a stale wiki. This is that design. Tools versus Resources as the decision the whole thing hinges on, output schemas derived from the descriptor model already published, why a read-only envelope has to be enforced rather than annotated, and why authorization — not the tool list — is the governance plane. Verified against MCP revision 2026-07-28.