Pinterest developed a Model Context Protocol (MCP) ecosystem to enable AI agents. MCP allows large language models to interact with tools and data using a unified protocol. The architecture consists of multiple domain-specific, cloud-hosted MCP servers. A central registry manages these servers, providing discovery and authorization. Engineers can write tools and the platform handles deployments. The platform integrated MCP into existing workflows, like the internal AI chat. Security is paramount, with a dedicated standard and two-layer authorization using JWTs and mesh identities. Business-group-based access gating mitigates risks for sensitive actions. Human-in-the-loop approvals are required for sensitive operations for safety. The system is designed to be observable, logging inputs and outputs for impact analysis. The MCP ecosystem is saving engineers significant amounts of time, with over 66,000 monthly invocations. Pinterest plans to expand MCP usage by adding servers and refining governance.