Discovering a service's MCP URL from its domain before addMcpServer

[NessGate]

The MCP client docs start from a known URL, for example:

await this.addMcpServer("weather", "https://weather-mcp.example.com/mcp", {
  transport: { type: "streamable-http" },
});

I often know the service domain but not its MCP URL. The SDK handles the connection once the URL is known, but there is still a discovery step before that.

I've been handling that with an open-source resolver called NessGate (disclosure: I maintain it). It takes a domain and returns the MCP endpoint and connection metadata, which can then be passed to addMcpServer:

const plan = await fetch("https://nessgate.com/connect/exa.ai", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    client: { supports: [{ protocol: "mcp" }] }
  }),
}).then((r) => r.json());

if (plan.outcome === "ready") {
  await this.addMcpServer("exa", plan.connection.endpoint, {
    transport: { type: "streamable-http" },
  });
}

Would this discovery step be useful as an MCP client example or short documentation note? Happy to put together an example if it fits the project.