Building a Production MCP Server — Auth, Logging, Versioning

Key Takeaways

• MCP servers in production must enforce OAuth token relay per tool endpoint — not a single shared credential — so that every invocation carries a verifiable caller identity for least-privilege enforcement and breach isolation.
• All tool calls must emit structured audit events (JSON, with tool_name, schema_version, caller_id, timestamp, and latency) to a centralised log sink; free-text logging fails compliance gates in regulated verticals like BFSI and legal.
• Tool schemas must be semantically versioned and served through a versioned registry; Claude must negotiate the schema version at session initialisation so that a schema change never silently breaks an in-flight workflow.
• Memory anchor: treat your MCP server exactly like an internal API gateway in a microservices mesh — auth middleware, structured access logs, and a versioned contract registry are non-negotiable before go-live.