Access Mastercom via your acquirer's API integration or the Mastercom portal; authenticate using OAuth 2.0 client credentials to obtain a token scoped to the dispute management endpoints.
Retrieve incoming chargebacks using GET /chargebacks and filter by status to identify cases requiring a response; note the response due date for each case.
Submit a first chargeback response (representment) via POST /chargebacks/{caseNumber}/responses with the appropriate claim type, reason code, and supporting document references within the acquirer's response window.
If the issuer responds with a second presentment (pre-arbitration), review the updated case details and decide whether to accept the pre-arbitration or escalate to arbitration via POST /chargebacks/{caseNumber}/arbitration within the pre-arbitration response window.
Upload supporting documents using POST /documents with the case number reference; link them to the response payload by including the document IDs.
Monitor case outcomes via GET /chargebacks/{caseNumber} and reconcile financial impacts against your settlement records.
Known gotchas
Mastercom pre-arbitration deadlines are strict; missing the pre-arbitration response window forfeits the right to escalate, accepting the financial liability.
Document uploads must be completed and the document IDs referenced in the response payload before submitting the response; uploading after submission will not associate the documents.
Case numbers and ARN (acquirer reference number) are different identifiers; Mastercom API calls use the case number, not the ARN, in path parameters.
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