Host multiple MCP servers with different HTTP endpoints in one process using keyed services

[flensrocker]

Is your feature request related to a problem? Please describe.

In my "modulith" (ASP.NET Core) application I want to provide multiple MCP servers/endpoints, so that every endpoint delivers a subset of tools, so that MCP clients are not "overwhelmed" by the amount of tools.

Describe the solution you'd like

I would like to register multiple MCP server as keyed services in dependency injection and call MapMcp multiple times with different routes providing the key used for the keyed services.

builder.AddKeyedMcpServer("key", ...) // etc.

app.MapKeyedMcp("key", "/mcp/key", ...) // etc.

Describe alternatives you've considered

I haven't considered alternatives, because keyed services seems natural for me. Only viable alternative would be "going microservices" and split the application into multiple containers.

[relusion]

I've built a library that addresses this use case.
(https://github.com/relusion/Mcp.AspNetCore.MultiHost)

It takes a slightly different approach than keyed services - each MCP host gets its own isolated DI container with configurable service bridging from the main application.

Usage example:

builder.Services.AddMcpMultiHost(options =>
{
    options.AddHost("admin", host =>
    {
        host.WithRoutePrefix("/mcp/admin")
            .ConfigureMcpServer(mcp => mcp
                .WithHttpTransport()
                .WithTools<AdminTools>());
    });

    options.AddHost("user", host =>
    {
        host.WithRoutePrefix("/mcp/user")
            .ConfigureMcpServer(mcp => mcp
                .WithHttpTransport()
                .WithTools<UserTools>());
    });
});

app.MapMcpMultiHost();

Features:

• Per-host DI isolation (tools in /mcp/admin are not visible in /mcp/user)
• Service bridging (share logging, config, custom services between hosts)
• Optional discovery endpoint (/mcp/_hosts)
• Works with existing MCP SDK public APIs

Feedback’s welcome... Thanks.