How to make private MCP server accessible by a declarative agent?

Noufal Shafeeq, If you're referring to a Microsoft 365 Copilot declarative agent using an MCP plugin, the key limitation is that the agent runs in Microsoft's cloud. That means it cannot directly connect to an MCP server that is only reachable on your company's private network unless that server is made accessible to the cloud.

Your options are:

1. Expose the MCP server securely
   • Publish the MCP server through a secure internet-facing endpoint (for example, behind a reverse proxy or API gateway).
   • Protect it with supported authentication (such as OAuth 2.0 or Microsoft Entra ID).
   • Restrict access using firewalls, IP allowlists, or other network controls.
   • Then configure your declarative agent to use that remote MCP endpoint.
2. Use a proxy or gateway
   • Instead of exposing your internal MCP server directly, deploy a gateway in a DMZ or cloud environment that forwards requests to the internal MCP server.
   • This preserves your internal network boundary while allowing the cloud-hosted Copilot agent to communicate with the MCP server.
3. Use an alternative integration pattern
   • If exposing the MCP server isn't permitted by your organization's security policies, consider exposing the required functionality through supported cloud-accessible APIs (for example, via a custom connector or another service) rather than having the declarative agent connect to the private MCP server directly.

At present, there isn't a mechanism for a Microsoft 365 Copilot declarative agent to tunnel into an on-premises/private-network-only MCP server automatically. The MCP endpoint must be reachable from the cloud-hosted Copilot service