Audit your current RETS queries: document every resource (Property, Member, Office), class, and field your application uses, along with any DMQL filter expressions
Obtain RESO Web API credentials from your MLS — most REALTOR-operated MLSs are now required to provide RESO Web API access; RETS is officially deprecated
Request the RESO Web API metadata document (GET /Property/$metadata) and build a mapping table from your RETS field names to RESO Data Dictionary equivalents
Translate DMQL filter expressions to OData $filter syntax; replace DMQL operators (=, ~, +) with OData equivalents (eq, contains, and)
Abstract your MLS integration behind an internal data access layer so you can switch the underlying transport without touching application logic
Run RETS and RESO Web API feeds in parallel for a validation period, diffing output records to catch mapping gaps before cutting over
Known gotchas
RESO has ended all certifications and support for RETS — do not invest further in RETS infrastructure; plan the migration as a finite project with a hard cutover date
DMQL queries often relied on MLS-specific field names and lookup codes that have no direct RESO equivalent; expect to spend significant time on lookup table translation
Some MLSs still transitioning may offer both RETS and RESO Web API simultaneously during a window — confirm the RETS sunset date with each MLS before decommissioning your RETS client
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp