MCP Best Practices: 7 Hard Lessons I Learned Building 5 MCP Servers (Full Checklists Included)

Short summary

After building 5 MCP servers over 3 months, the author shares hard-won lessons about production reliability. Critical practices: return human-readable messages instead of empty arrays (prevents client hangs), use framework JSON serialization instead of manually building strings (prevents parsing errors), and support multiple authentication header locations since MCP clients remain inconsistent on standards. Implementing these defensive coding patterns fixes 80% of integration failures.

• •Return human-readable messages when queries return no results, not empty arrays—prevents client hangs
• •Always use framework JSON serialization; never manually build JSON strings to avoid parsing errors
• •Support multiple authentication methods (Bearer, X-API-Key, query params) since MCP clients lack consistency

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