A governed MCP gateway for enterprise agents

The challenge

The firm had dozens of internal MCP servers and agents that needed to reach them. Without a central gateway, there was no single place to control which callers could use which tools, and agents struggled to route a natural-language request to the right server.

What we built

• ✦Built on the open-source MCP Gateway & Registry: an nginx data plane, a FastAPI registry, and an OAuth2/OIDC auth server
• ✦Hybrid BM25 and vector retrieval, followed by LLM reranking to pick the right tool from the top candidates
• ✦RFC 8693 on-behalf-of token exchange, so agents act with the calling user's identity
• ✦Staleness and drift detection, failover and SLA monitoring, and a CSV bulk importer for onboarding servers
• ✦Deployed on AWS ECS with Terraform, and decisions recorded in ADRs

Security & compliance

• ✦Rights enforcement separates agentic callers from GenAI-only callers. Machine tokens are blocked from human-only servers
• ✦Unknown callers are denied by default, and every decision writes an audit line
• ✦SSO through Keycloak and Okta, with scope-based access control
• ✦Routing measured on held-out queries with significance testing. Self-written test queries had inflated accuracy by about 30 points

Stack