Retrieve fare rules for the selected fare basis code via the booking API's fare rules endpoint or directly from an ATPCO-connected data feed, specifying the origin-destination and carrier
Locate Category 16 (Penalties) in the fare rule text or structured data: extract the change fee amounts or percentage, the refund penalty, and any no-show penalty applicable before and after departure
Locate Category 31 (Voluntary Changes / Reissue) if present: this category governs whether the fare allows reissue, the permitted routing changes, and any additional collection requirements beyond the change fee
Present the penalty summary to the user in plain language prior to booking, noting applicable conditions (advance purchase cutoffs, travel window restrictions)
At the time of a change or refund, re-fetch the rules to confirm no waiver or emergency override applies before calculating and collecting fees
Known gotchas
CAT16 penalty amounts may be expressed as a fixed fee, a percentage of the fare, or whichever is higher — parse all three structures and compute accordingly
CAT31 reissue conditions are frequently absent or minimal for fully flexible fares, but fully populated for semi-flex fares; absence of CAT31 data does not mean reissue is free — fall back to CAT16 change fee logic
Fare rules retrieved at search time may differ from those at ticketing if an interim schedule or fare update occurred; always re-validate rules immediately before presenting fees to the user
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