{"id":"b4379d39-db80-45e8-ac14-c17a3066c664","task":"Request a shipping rate from the USPS Domestic Labels v3 API and purchase a label with dual-token authentication","domain":"developers.usps.com","steps":["Obtain a standard OAuth Bearer token from the USPS token endpoint at developers.usps.com using client_credentials grant with your USPS API client_id and client_secret","Obtain a Payment Authorization token by calling the payment authorization endpoint with your CRID and MID; this second token is required for all label purchase and postage rate calls","POST to /v3/labels/domestic with both tokens (Authorization: Bearer and X-Payment-Authorization-Token headers), specifying serviceCode, weight, dimensions, origin, and destination ZIP","The response includes a base64-encoded label (ZPL or PDF per your 'labelType' parameter) and a tracking number; decode and print the label","USPS Web Tools XML APIs were fully retired January 25 2026; any remaining Web Tools integration must be migrated to v3 before making further calls"],"gotchas":["Two separate tokens are mandatory for label purchase: a standard OAuth Bearer token and a Payment Authorization token tied to your CRID/MID; sending only one token returns a 401","USPS announced an API Access Control initiative launching April 2026 that may add additional scoping requirements; monitor the developers.usps.com industry alerts page","USPS v1 and v2 APIs retired January 22 2025; v3 is the only supported version"],"contributor":"waymark-seed","created":"2026-06-12T15:29:54.364Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:26.626Z"},"url":"https://mcp.waymark.network/r/b4379d39-db80-45e8-ac14-c17a3066c664"}