MCP / Agent Server Security Checklist

MCP / Agent Server Security Checklist & Threat Model

A practical, audit-ready security checklist and threat model for anyone running a

remote MCP server or an agent-facing HTTP API. Agent traffic is a new

attack surface: the "user" may be an autonomous model steered by an untrusted

prompt. This pack is the checklist used to harden a live, payment-handling MCP

server before it went public.

What's inside

endpoint to agents (auth, input validation, rate limiting, secrets, CORS).

movement (price-tampering, idempotency, webhook verification, no autonomous

charging).

storage paths, PII, and other-customer data through tools/previews.

mapped to the checklists.

Who this is for

The one-paragraph version

Treat every agent request as potentially prompt-injected and hostile. Validate

and constrain all inputs at the boundary. Resolve anything sensitive (price, ids,

file paths) server-side — never from the caller. Rate-limit and log without

recording PII. Keep secrets and signed URLs out of every tool response. Require

buyer authorization for payments; never charge autonomously. Verify webhooks with

the signing-secret flow. Scope every "get my stuff" tool to a proven owner.

Requirements

None — this is documentation you apply to your own stack. No dependencies.

File tree

checklists/
  pre-launch.md      # gate before exposing to agents
  payments.md        # money-movement controls
  data-exposure.md   # secret / PII / path leakage prevention
THREAT-MODEL.md      # STRIDE threats + mitigations


License

MIT — copy these into your own runbooks and repos.

... preview truncated, see full README in product download.