Most programmatic car rental access goes through aggregator APIs (e.g. Rentalcars Connect, CarTrawler, Holidaycars API) rather than direct OTA APIs from individual rental companies; authenticate using your API key and partner credentials.
Search for availability by POSTing pickup location (IATA airport code or lat/lng), dropoff location, pickup datetime, dropoff datetime, and driver age (affects pricing in many markets); the response returns a list of vehicle categories with base rates.
Each result includes a rate_plan_id or rate_code — store this verbatim; booking requires passing it back unchanged, and rates can change between search and book.
Inspect the included_insurances[] and optional_extras[] fields: CDW (Collision Damage Waiver) and TP (Theft Protection) may be included in the base rate for some results but not others — surface this clearly before presenting a 'from' price.
Create the booking by POSTing the rate_code, driver details (name, license country, age), and selected optional extras; store the booking reference and the rental company's own voucher number separately.
Always surface the excess/deductible amount (the amount the driver is liable for even with CDW) — this is different from having no CDW at all, and many users confuse CDW with full coverage.
Known gotchas
Insurance definitions vary by country and rental company — CDW in the US context often differs from CDW in Europe; never assume a term means the same thing across markets without checking the rate's policy details.
Young driver surcharges and one-way fees are often added at the counter, not at booking — if these are not returned in the API, warn the user that additional charges may apply.
Car rental no-show policies vary: many reservations are held without charge but some rate types (prepaid, non-refundable) charge the full amount on no-show — parse the cancellation_policy field carefully and surface it to users.
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