The eCardWidget MCP server is designed so an AI assistant can act in your account without being able to exceed what you explicitly allowed. This document is the threat model and the controls.
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Least privilege by construction. The server authenticates with a single scoped API key that you generate and configure per-area (
none/view/manage). The key's scope is the hard ceiling. -
Server-side enforcement is the real guarantee. The eCardWidget API independently enforces the key's scope on every request (403 on anything out of scope), throttles it (120 req/min by default), and audits every use. The MCP server's client-side tool-hiding is UX + defense-in-depth, not the security boundary — a compromised client still cannot exceed the key's scope.
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Introspection-driven exposure. On startup the server calls
GET /v2/api/key/infoand registers only the tools the key is authorized for. The model never even sees tools it can't use.
| Risk | Control |
|---|---|
| Over-broad access | Per-area scoped keys; server-side 403 on out-of-scope calls. |
| Secret leakage | API key read from ECW_API_KEY env only; never logged; /key/info returns no key values. |
| Destructive / high-blast actions | Two-phase confirm: a dry-run preview + one-time token first, then execute. |
| Rate abuse / runaway loops | Server throttles per key; the client honors 429 + Retry-After with backoff. |
| Tool poisoning / prompt injection | Tool descriptions are static and contain no user/account content; inputs are schema-validated (zod). |
| Stdout corruption | All diagnostics go to stderr; stdout is reserved for the MCP JSON-RPC channel. |
Every tool carries MCP tool annotations — readOnlyHint,
destructiveHint, idempotentHint, openWorldHint. These are hints for clients, not guarantees;
the guarantees are the scoped key + server-side enforcement + the two-phase destructive flow.
- Store it in your MCP client's config
env(or a secret manager), never in source control. - Scope it to only what the assistant needs; rotate it if exposed (Settings → Developers → API Keys).
- Revoking the key in the dashboard immediately disables this server.
Found a security issue? Email security@ecardwidget.com. Please do not open a public issue for vulnerabilities.