MCP 2026-07-28

MCP 2026-07-28 is the first revision without a session. Moka speaks it and the 2025 revisions, and shows which one each server uses: Settings → MCP servers shows a badge such as MCP 2026-07-28 next to the server’s name.

What changed

	2025-11-25 and earlier	2026-07-28
Opening	initialize handshake, then a session	server/discover, no session; each request carries the client’s version and identity in _meta
Server asks the client for something (sampling, elicitation, roots)	The server sends its own request mid-call	The server answers the call with input_required; the client calls again with the answers
Change notifications	Sent whenever the server likes; resources/subscribe for a resource	Only on a subscriptions/listen stream the client opens
Tasks	In the core spec	An extension

How sampling works now

In 2025, a tool that wanted your model sent sampling/createMessage to the client in the middle of tools/call, and waited.

In 2026-07-28 the server can’t send requests to the client. Instead:

1. The client calls tools/call brainstorm.
2. The server answers right away with resultType: "input_required": “first, run this completion” (inputRequests.ideas is a sampling/createMessage request), plus an opaque requestState.
3. Moka shows you the sampling request, as before. You approve, and it runs on the workspace’s model.
4. Moka calls tools/call brainstorm again, a new request with the completion in inputResponses.ideas and the same requestState.
5. The server finishes the tool and returns the result. A server can ask more than once (round 3, 4…), up to 10 rounds.

Elicitation (forms, URLs) and roots work the same way. Approval, auto-allow and deny (the server’s Sampling requests setting) are unchanged.

Note

Refusing is different. In 2025 the server got the error back and decided what to tell the model. In 2026-07-28 a retry can’t carry an error, so when you reject a sampling request the tool call ends in Moka, with User rejected sampling request, and the server never hears about it.

Sampling, roots and logging are deprecated in 2026-07-28, but stay in the spec for at least 12 months. Moka supports them in both revisions.

In the inspector

You see	Meaning
server/discover · asked on a separate copy of the server	On stdio, the SDK asks a short-lived second copy of the server which revisions it speaks, so the exchange isn’t on the session’s pipe. Moka shows it anyway
input required badge on a request	The server needs something first; the reply lists what (sampling/createMessage, elicitation/create, roots/list)
tools/call #5 · round 2 with ideas	The client’s retry, with the answers by key. It belongs to the same tool call (and the same attempt in Attempts)
subscriptions/listen	The stream that carries list_changed and resources/updated. Subscribing to a resource replaces the stream with one that includes its URI

Choosing the version

Each server has an MCP version setting (Settings → MCP servers → Advanced options), protocol in moka.json:

protocol
"auto"	Ask with server/discover; use 2026-07-28 if the server offers it, else 2025. Default for HTTP servers and the demo server
"2025"	The classic initialize handshake. Default for stdio and SSE servers, so Moka starts each local server only once
"2026"	2026-07-28 only; fails if the server doesn’t offer it

Tip

On stdio, auto starts a short-lived copy of the server to ask server/discover. That’s harmless for most servers, but if yours does work at startup (migrations, logins), set "2025" or "2026".

Try it

The demo server speaks both revisions, from one codebase (TypeScript SDK v2, serveStdio). Ask “Brainstorm names for a coffee robot” or “Order me a coffee”, then open the inspector’s RPC tab. Set the demo server to 2025 to see the same tools work through sampling/createMessage and elicitation/create requests instead.

Editors behind Moka’s proxy that use 2026-07-28 are recorded the same way. The proxy view shows the version the editor asked for.