Realtime MCPs

[viktormarinho]

This looks like MCP resources. It could be a worse or better version of them.

I believe there is some way that you can toggle a "realtime mode" in an MCP, and then when you do this, the URL of the MCP starts to be kind of a proxy to some cloudflare durable object we put on top of it and we add realtime capabilities.

So, this enables us to configure the entity/revalidation relationship between tools.
And then our Worker can be connected to in a Convex-like DX. I can easily then generate/create views that are realtime.

Pseudo code:

import { useToolQuery, useToolMutation } from "@/hooks/tool";

export default function RealtimeToolTable() {
  // Live subscription to the "listRecords" tool
  const records = useToolQuery("tools/records/list", {
    workspaceId: "abc123", // or fetched from context
  });

  // Mutation tool to create new record
  const createRecord = useToolMutation("tools/records/create");

  return (
    <div className="p-4 space-y-4">
      <h1 className="text-xl font-semibold">Live Records Table</h1>

      <button
        onClick={() => createRecord({ name: "Untitled", status: "new" })}
        className="px-3 py-2 bg-blue-600 text-white rounded"
      >
        Add Record
      </button>

      <table className="min-w-full border mt-4">
        <thead className="bg-gray-100 text-left">
          <tr>
            <th className="px-4 py-2">ID</th>
            <th className="px-4 py-2">Name</th>
            <th className="px-4 py-2">Status</th>
          </tr>
        </thead>
        <tbody>
          {records?.map((record) => (
            <tr key={record.id} className="border-t">
              <td className="px-4 py-2">{record.id}</td>
              <td className="px-4 py-2">{record.name}</td>
              <td className="px-4 py-2">{record.status}</td>
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
}

Assumptions / Ideas Behind This Pseudocode:
useToolQuery(toolPath: string, input: object):

Connects to a Durable Object websocket behind the MCP’s new realtime proxy mode.

Automatically revalidates on updates, similar to Convex's useQuery.

useToolMutation(toolPath: string):

Returns a function that executes a tool call (e.g. via fetch or internal protocol).

The server knows which queries are invalidated by which mutations based on the entity revalidation config.

Durable Object (or internal system) does:

Tracks subscriptions.
Pushes updates over websocket.
Invalidates and resends when a mutation affects a tool’s result set.

[pedrofrxncx]

yeah, that looks good. if the server advertises its resource capabilities, we should allow this connection type.
we could also connect the user’s browser to the mcp‑client through another WebSocket, making it easy to push notifications to the UI.
@mcandeia suggested using SSE; i’m fine with either, but I’d like to add this issue to our discussion: modelcontextprotocol/modelcontextprotocol#493

[vibe-dex]

SSE feels like the best starting point here. It’s simpler, works great for one-way updates, auto-reconnects, and aligns with Cloudflare’s existing patterns. WebSocket would be a solid future upgrade for multiplexing and bi-directional flows, but it brings more client/server complexity (reconnects, custom protocols).

Also, it would be awesome if the MCP could advertise whether a tool supports realtime (maybe via metadata). The client hook could then auto-upgrade to live mode when available.

Overall, I love this idea, makes AI feel like I'm using Figma or Slack or Notion.

PS: Strongly recommend defining a clear tool ↔ entity invalidation map so the Durable Object knows what to broadcast.

[lucis]

What's the "Convex-like" DX for MCP apps?