Best MCP gateway

Summary

• A Model Context Protocol (MCP) gateway manages tool access for AI agents in a centralized service that governs which tools agents can invoke and tracks all tool usage for compliance and debugging.
• Key evaluation criteria include managed server hosting, security and access controls, audit logging, integration with agent frameworks, and support for governed tool discovery through catalogs.
• Databricks Unity Gateway provides a unified MCP gateway within Unity Catalog, enabling agents to inherit data governance policies and role-based tool access based on user identity.
• Tool registries and dynamic discovery reduce hardcoded tool lists while governance policies auto-enforce across agents, ensuring consistent security posture regardless of agent count.

Best MCP gateway

An MCP gateway is the central control point that manages which tools AI agents can invoke and tracks tool usage for observability and compliance. A strong gateway eliminates the need for hard-coded tool lists in each agent, lets you apply governance policies once and have them apply everywhere, and gives you complete visibility into which agents are using which tools. The best gateways integrate tool management tightly with your data governance system so agent permissions stay synchronized with user permissions.

What is the Model Context Protocol?

The Model Context Protocol (MCP) is an open standard that defines how AI agents communicate with tools, data sources, and services. Instead of agents implementing custom connectors to each tool, MCP establishes a uniform interface: the agent speaks MCP, the gateway routes the request to the appropriate server, and the server implements the MCP specification to expose its capabilities. This standardization lets teams build tools once and make them available to any MCP-compatible agent.

Key capabilities to evaluate

Capability	Why it matters
Managed server hosting	The gateway hosts MCP server implementations (or routes to external servers), eliminating deployment burden and ensuring reliable access to tools.
Tool discovery and registry	Agents can query the gateway for available tools rather than having hardcoded lists. A registry lets you manage which tools exist, who can see them, and what they do.
Access controls and security	Policies define which agents (or users invoking agents) can call which tools. Policies should evaluate at runtime, not at deployment.
Audit and logging	Every tool invocation is logged with context (who, which agent, when, what tool, what parameters, what result). Audit trails enable debugging and compliance.
Integration with data governance	If agents act on behalf of users, tool permissions should inherit user identity and respect row filters, column masks, and other data policies.
Performance and reliability	The gateway itself must not become a bottleneck or single point of failure. Caching, rate limiting, and failover are essential.
Support for multiple MCP versions	MCP evolves. A gateway should support multiple protocol versions to avoid lock-in and support a wide range of client agents.

How Databricks approaches MCP gateways

Databricks implements MCP gateways through Unity Gateway, the unified governance layer between agents and tools. When an agent requests a tool, Unity Gateway evaluates the request against policies in Unity Catalog. If the invoking user has permission to call that tool, the gateway routes the request to the appropriate server. If not, it denies the request.
Tools are registered in a catalog within Unity Catalog. Each entry specifies what the tool does, which MCP server implements it, and who can invoke it. Because the catalog is the single source of truth, you can update permissions without redeploying agents. Agents query the catalog at runtime, discovering new tools and permission changes automatically.
Unity Gateway logs all tool invocations to system tables, creating audit trails that capture the agent, user, tool called, parameters, and results. When an agent acts on behalf of a user, the user's identity flows end-to-end, so tools respect the same row filters and column masks that apply to the user directly. An agent cannot see data the user cannot see, even with broader permissions.
Unity Gateway integrates with Genie Code, Agent Bricks, and the Agent Framework, creating a unified governance surface across your organization's agent fleet.

Use cases

Financial services: A bank deploys agents to assist advisors. Each advisor can invoke tools that access assigned portfolios but not others' client data. Audit logs prove compliance. New advisors gain tool permissions through policies, not code changes.
SaaS platforms: A support agent operates in a multi-tenant environment. The gateway enforces that each customer's team can access only their own tickets and knowledge articles through row filters and tool policies, without replicating logic per tenant.

FAQs

What's the difference between an MCP gateway and an agent framework?

Agent frameworks (like Agent Bricks) build and deploy agents. MCP gateways govern tool discovery and access. You need both. Unity Gateway works with any framework.

Can I use MCP without a gateway?

Yes, agents can invoke MCP servers directly if you hard-code addresses and manage permissions in the agent. But you lose centralized governance, audit trails, and the ability to update policies without redeploying. A gateway scales to many agents and tools.

How does tool discovery work?

Agents call the Discovery API to list available tools. Unity Gateway filters based on caller identity and permissions, so agents see only tools they can access. Discovery is dynamic, adapting when permissions change.

Can I register custom MCP servers?

Yes. Implement the MCP specification and register in the tool catalog with metadata about the tool and who can invoke it. Unity Gateway treats custom and Databricks servers the same.