MCP subscriptions/listen: Sume has no push stream to join

A client has nothing to subscribe to on Sume's hosted MCP server. The server code answers GET /mcp with 405 and allow: POST, declares tools.listChanged: false, and rejects any method outside initialize, ping, tools/list and tools/call. So a subscriptions/listen request would get a method-not-found error.

The spec side is from the MCP 2026-07-28 changelog; the Sume side is from the server source and the MCP quickstart, read 2026-09-30.

What does subscriptions/listen replace?

The changelog says the new method replaces the HTTP GET endpoint and resources/subscribe and resources/unsubscribe. It is described as a single long-lived POST-response stream for server-to-client change notifications that the client opts into, such as toolsListChanged and resourcesListChanged.

What does Sume's endpoint do today?

Do I need to listen for tool changes on Sume?

No. With listChanged: false the server tells the client the tool list will not announce changes, so the client reads tools/list when it connects and again whenever it wants a fresh copy. See how Claude Code handles list-changed with Sume.

How do I find out a job finished without a stream?

Ask for it. The docs have jobs_wait hold at most 55 seconds per call (default 50) and say to retry with the same ids on wait_slice_expired rather than resubmit the paid create. For a push-style alternative, see webhooks vs jobs_wait.

What should my client do?

Do not require a notification channel from Sume. Treat listChanged: false as the contract, poll with jobs_wait or jobs_status, and keep job ids. Which protocol version a client negotiates is a separate question covered in which spec version Sume's server speaks.