Before deploying MCP servers in production, verify these 12 controls. Based on the risks outlined in our MCP Security Risks guide.

Input & validation

1. ✅ Validate all tool parameters — Use Zod (TypeScript) or Pydantic (Python). Never trust raw LLM output.

2. ✅ Sanitize tool responses — Strip potential prompt injection from data returned by tools.

3. ✅ Rate limit tool calls — Prevent runaway agents from making thousands of calls.

Authentication & authorization

4. ✅ Authenticate remote connections — For SSE transport, require API keys or OAuth. Never expose servers without auth.

5. ✅ Implement per-user permissions — Check user permissions on every tool call, not just at connection time.

6. ✅ Use least privilege — Each server only accesses what it absolutely needs.

Isolation & containment

7. ✅ Sandbox MCP servers — Run in Docker containers or separate processes.

8. ✅ Network segmentation — Internal servers (database, files) should not have outbound internet access.

9. ✅ Separate read and write — Consider separate servers for reading vs writing. AI reads freely, needs approval to write.

Monitoring & audit

10. ✅ Log every tool call — Record: timestamp, tool name, parameters, user, result.

11. ✅ Alert on anomalies — Flag unusual patterns: high volume, unexpected tools, off-hours access.

12. ✅ Human approval for destructive actions — Delete, send, deploy, pay — require confirmation.

Quick implementation

Most of these controls can be added in under an hour. Start with the top 3:

1. Input validation (Zod/Pydantic) — 15 minutes
2. Logging every tool call — 15 minutes
3. Least privilege (review what each server accesses) — 30 minutes

Then add auth, sandboxing, and monitoring as you move toward production.

Testing your security

Before deploying, try to break your own MCP server:

• Send SQL injection in tool parameters
• Include prompt injection in tool responses
• Try accessing resources outside the allowed scope
• Test with missing or invalid auth tokens

If any of these succeed, fix them before production.

For GDPR compliance

Also verify: data processed by MCP servers is covered by your DPA, personal data doesn’t flow through non-compliant providers, and consider self-hosting for sensitive data.

Related: MCP Security Risks · MCP Complete Guide · Self-Hosted AI for GDPR · Best Password Managers for Developers