generated: '2026-08-13' method: derived source: >- Derived by binding the published tool list in mcp/mailchimp-mcp.yml (Mailchimp Transactional Messaging MCP server, documented at https://mailchimp.com/developer/transactional/guides/how-to-use-mailchimps-transactional-messaging-mcp/) to operationIds verified in openapi/mailchimp-transactional-api-openapi-original.json (Mailchimp Transactional API 1.4.1) and openapi/mailchimp-marketing-api-openapi-original.json (Marketing API 3.0.91), both harvested 2026-08-13. description: >- What the Mailchimp MCP surface can do versus what the REST surface can do. The hosted MCP server covers the TRANSACTIONAL API ONLY, and most of its tools are meta-tools — they describe, diagnose or proxy the API rather than mapping to one operation. The entire Marketing API (298 operations) has no first-party MCP tool at all. Live tools/list introspection is auth-gated, so input schemas were not read from the server; bindings below are by name and documented semantics. surfaces: openapi: - file: openapi/mailchimp-transactional-api-openapi-original.json api: mailchimp:mailchimp-transactional-api operations: 99 gated: false - file: openapi/mailchimp-marketing-api-openapi-original.json api: mailchimp:mailchimp-marketing-api operations: 298 gated: false graphql: endpoint: null note: >- The only Mailchimp GraphQL surface is Open Commerce (formerly Reaction Commerce), a discontinued self-hosted stack with no Mailchimp-operated endpoint. See graphql/mailchimp-graphql.md. mcp: url: https://mandrillapp.com/mcp transport: http gated: true probe: fetched: '2026-08-13' method: 'POST tools/list (jsonrpc 2.0)' http_status: 200 body: '{"jsonrpc":"2.0","error":{"code":-32001,"message":"Authorization: Bearer required"},"id":null}' note: >- The endpoint is live and answers JSON-RPC, but tools/list requires a Transactional API key as a bearer token. Tool names and descriptions below come from Mailchimp's published guide, not from an authenticated introspection, so no inputSchema was captured. crosswalk: - tool: account_status category: account rest: [postUsersInfo, postUsersPing] binding: rest confidence: high note: /users/info returns account reputation, quota and backlog; /users/ping is the credential check. - tool: call_api category: proxy rest: ['*'] binding: rest confidence: low note: >- A generic proxy tool — it can invoke any Transactional endpoint, so it fans out to all 99 operations rather than binding to one. Its real input contract is the endpoint name plus that endpoint's own parameters. - tool: describe_api category: introspection rest: [] binding: none confidence: high note: >- Returns the parameters/schema of a named Transactional endpoint — a server-side read of the same spec captured in openapi/. No REST operation exposes this. - tool: list_api category: introspection rest: [] binding: none confidence: high note: Enumerates available Transactional endpoints; a spec-listing helper with no REST equivalent. - tool: diagnose_failed_send category: troubleshooting rest: [postMessagesInfo, postMessagesSearch, postRejectsList] binding: rest confidence: medium note: >- A composite. The underlying facts come from message info/search plus the rejection (denylist) registry; the diagnosis itself is server-side reasoning. - tool: build_template category: content rest: [postTemplatesAdd, postTemplatesUpdate, postTemplatesRender] binding: rest confidence: low note: >- Template construction assistance. Persisting or rendering a template maps to the /templates operations, but the drafting step has no REST equivalent. - tool: integrate_api category: guidance rest: [] binding: none confidence: high - tool: onboarding category: guidance rest: [] binding: none confidence: high - tool: submit_feedback category: meta rest: [] binding: none confidence: high mcp_only: - tool: describe_api reason: Spec introspection served by the MCP host; the equivalent for a REST client is reading the OpenAPI. - tool: list_api reason: Endpoint enumeration served by the MCP host; no /endpoints operation exists in the API. - tool: integrate_api reason: Documentation/guidance generation, not an API capability. - tool: onboarding reason: Guided account setup, not an API capability. - tool: submit_feedback reason: Feedback channel to Mailchimp; no public REST endpoint. rest_only: - capability: Marketing API — the entire surface api: mailchimp:mailchimp-marketing-api operations: 298 note: >- Audiences, members, tags, segments, campaigns, content, automations, journeys, reports, e-commerce stores/orders/products, file manager, templates, landing pages, batches and webhooks. No first-party MCP tool exists for any of it; mcp/mailchimp-mcp.yml carries an API Evangelist candidate tool set, not a Mailchimp server. - capability: Transactional — inbound email processing operations: [postInboundDomains, postInboundAddDomain, postInboundRoutes, postInboundAddRoute, postInboundSendRaw] - capability: Transactional — dedicated IP and pool management operations: [postIpsProvision, postIpsStartWarmup, postIpsSetPool, postIpsCreatePool, postIpsCheckCustomDns] - capability: Transactional — webhook registration operations: [postWebhooksAdd, postWebhooksList, postWebhooksUpdate, postWebhooksDelete] - capability: Transactional — subaccounts operations: [postSubaccountsAdd, postSubaccountsList, postSubaccountsInfo, postSubaccountsPause, postSubaccountsResume] - capability: Transactional — exports and activity search operations: [postExportsActivity, postExportsRejects, postExportsList, postMessagesSearchTimeSeries] coverage: tools_named: 9 tools_bound_to_rest: 4 tools_mcp_only: 5 rest_operations_total: 397 rest_operations_transactional: 99 rest_operations_marketing: 298 rest_operations_with_a_tool: 8 note: >- Excludes the generic call_api proxy from the bound count for rest coverage — it can reach any endpoint but names none. Marketing API coverage by first-party MCP is zero.