Authenticate requests using HTTP Basic Auth with your client_id as the username and your API key as the password; include the Accept: application/vnd.mx.api.v1+json header
Create or retrieve a User: POST /users with metadata or id to represent the end user in MX's system; note the user guid
Connect an institution: POST /users/{user_guid}/members with institution_code and credentials array to create a Member; MX initiates aggregation automatically on member creation
Poll GET /users/{user_guid}/members/{member_guid} until connection_status is CONNECTED; handle MFA challenges by checking for CHALLENGED status and posting challenge answers to POST /users/{user_guid}/members/{member_guid}/challenges
Fetch aggregated data: GET /users/{user_guid}/accounts for all accounts and GET /users/{user_guid}/transactions for transactions; use page and records_per_page query params for pagination
Known gotchas
Aggregation is asynchronous; data may not be immediately available after member creation — poll the member status or use MX webhooks rather than immediately fetching accounts and transactions
MX credential handling is sensitive; credentials are passed through MX's encrypted vault and should never be logged or stored in your own systems
Transaction data is MX-enhanced (categorized, cleaned, deduplicated) which means transaction IDs and descriptions may not match raw bank statement data — account for this when reconciling with other data sources
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