How to build a private enterprise MCP subregistry for secure agentic integration

The official MCP Registry (registry.modelcontextprotocol.io) is explicitly designed for public, open-source tools. Its specification states: 'The MCP Registry does not support private servers.' This creates a massive architectural gap for enterprises that cannot publish internal capabilities publicly. The solution is an Enterprise Subregistry — a private, curated clearinghouse that implements the MCP Registry's OpenAPI specification behind corporate firewalls. Slickrock.dev builds these Enterprise Subregistries with three critical security layers: (1) Tokenized Capability Scopes that ensure external agents can only access specific data partitions (e.g., one warehouse's inventory, not company-wide margin metrics), (2) Zero-Trust Security Gateways acting as firewalls between the open A2A mesh and internal SQL backends, and (3) Compliance Auditing that logs every millisecond of machine negotiation for HIPAA, SOC2, or financial regulatory tracking. This is the core commercial play: you are not competing with Salesforce AgentExchange or the public MCP Registry. You are building your client's Internal Capability Gateway using standardized protocols — putting the universal adapters on their engine so they can securely plug into the global agentic grid.