The LetsFG MCP server gives agents free flight search and booking after a one-time zero-amount card verification, plus hotel booking that always requires a card on file and a 10% reservation fee. Key risks are the mandatory saved payment method for hotel calls, the non-refundable reservation fee, the need to poll asynchronous hotel bookings rather than retry blindly, and avoiding accidental use of the separate paid Developer API registration commands.
LetsFG is the upstream MCP server for the LetsFG travel product, giving AI agents search across hundreds of airlines and the major booking sites plus bookable hotel rates with free-cancellation and pay-later terms. Search and flight booking run on LetsFG's own cloud engine; access requires a one-time, zero-amount card-on-file setup (letsfg auth) that yields a 90-day Bearer token, after which flight search and booking are free with no LetsFG fee. Hotel calls — including search — require a saved payment method on every request; booking charges a 10% non-refundable reservation fee up front, with the remaining balance paid directly to the supplier via a returned pay_link. The repo also documents a separate paid Developer API (prepaid credits, direct airline booking URLs) for high-volume commercial use, but the README explicitly warns agents not to call that product's registration/payment-setup commands.
letsfg auth once — a zero-amount card-on-file setup (nothing charged) that saves a 90-day Bearer token locally. 3. After that, flight search and booking work immediately with no LetsFG fee. 4. For hotel tools, ensure a valid payment method stays on file, since every hotel search and booking call requires one. 5. Only set the LETSFG_API_KEY environment variable if deliberately switching to the separate, paid Developer API — the README states most agents should not do this and should never call letsfg register or letsfg setup-payment.{"mcpServers":{"letsfg":{"command":"npx","args":["-y","letsfg-mcp"]}}}