Debug Freshness

Find the one object causing a freshness problem. Explain why it is behind. The report must name the culprit, show the evidence, and point to the SQL causing the expensive work.

Tools

This skill runs on the Materialize developer MCP server, which exposes two read-only tools. query_system_catalog reads mz_*, pg_catalog, and information_schema. query takes a cluster and runs everything else: EXPLAIN statements and mz_introspection relations. Client configuration prefixes them with the server name, as in mcp__<server>__query_system_catalog.

The EXPLAIN commands, their output columns, and the operator patterns are in references/dataflow-analysis.md. Each step below names the exact command it needs.

Workflow