What Credible Reads
Your published data sources (.tds / .tdsx) — calculated fields, default aggregations, folders, and the logical/physical data model — plus the calculated fields embedded in workbooks (.twb). These files are all the agent needs to translate. Connecting the official Tableau MCP server (tableau/tableau-mcp, hosted at mcp.tableau.com) is optional: it reads model metadata via the Metadata API and validates through the VizQL Data Service.
What Comes Across
The everyday modeling carries over. Here’s how the bigger pieces land — and where they get better:The Migration Flow
Credible reads the data source and workbook calcs, translates fields and relationships to Malloy, enriches with#(doc)/#(index) tags, and — where you connect it — validates row-by-row against the VizQL Data Service.
What Credible Handles
- LOD expressions encode a grain independent of the viz. A
{ FIXED [Customer ID] : SUM([Amount]) }becomes a Malloy aggregate at an explicit grain. Credible also distinguishes “real” LODs from workaround LODs that only existed to dedupe joins — the latter are unnecessary in a clean model. - Table calculations run over the rendered viz and depend on Compute-Using direction. They’re reconstructed as explicit Malloy window functions with a declared
partition_by/order_by;TOTAL()maps toall(). - Workbook-embedded calculated fields — business logic frequently lives in
.twb, not the published.tds, so Credible scans both. - Viz-level formatting — Compute-Using direction, table layout, cosmetic styling — is presentation and is dropped; threshold-based color rules become model logic, and model-worthy defaults and labels carry over.
Before & After
Tableau calculated fields as authored against a data source:FIXED LOD becomes an aggregate declared at its grain; table calcs become explicit window calculations. Purely visual constructs — Compute-Using direction, quick table calcs, worksheet formatting — have no model equivalent and are dropped.
More than a reformat. Logic that lived inside workbooks becomes a reusable, AI-discoverable model that serves every surface, not just Tableau — and Malloy’s symmetric aggregates keep totals correct where Tableau needed LODs to avoid double-counting. See what you gain →
Next Steps
Migration Overview
The method behind every migration
Metadata & Discovery
Tune your migrated model for AI retrieval