Apply for CarTrawler partner access and obtain your client ID and sandbox credentials from the partner portal.
Send an OTA_VehAvailRateRQ XML request (OTA 2015B schema) with pick-up/drop-off location codes, date range, and your client ID to the sandbox endpoint to retrieve available vehicle rates.
Parse the OTA_VehAvailRateRS response: extract VehAvailCore elements including vehicle class (ACRISS code), rate amounts, and rate key for the chosen offer.
Send an OTA_VehResRQ request referencing the selected rate key, driver details, and optional extras (GPS, child seat) to create the reservation.
Parse OTA_VehResRS: capture the confirmation number, supplier confirmation code, and any outstanding payment or deposit instructions.
Before go-live, switch base URL from sandbox to production, re-test a round-trip search-to-book flow, and confirm rate reconciliation matches the supplier invoice.
Known gotchas
CarTrawler uses partner-negotiated rate keys that expire; re-search if more than a few minutes elapse between availability check and reservation creation.
ACRISS codes from CarTrawler represent a vehicle category, not a specific model — display the category description to users rather than implying a guaranteed car model.
Sandbox responses may include dummy supplier confirmation codes that differ from production format; update any validation regex before going live.
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