Deprecated in MCP: Roots, Sampling, Logging and the HTTP+SSE transport | Portkeel
The 2026-07-28 revision deprecated Roots, Sampling, Logging and the HTTP+SSE transport, and it introduced a twelve-month minimum deprecation window. Deprecated is not removed: these features still respond today. The planning mistake is treating “still responds” as “still supported”. A feature on the clock needs a replacement plan before the window closes, not after it breaks.
The new lifecycle policy
Before 2026-07-28, deprecation timelines were informal. The new policy sets a twelve-month floor, which is a genuine improvement and also a trap: twelve months feels far away until it is a quarter away and nobody owns the work.
What each deprecation replaces
| Feature | Replaced by |
|---|---|
| HTTP+SSE transport | Streamable HTTP |
| Roots | Explicit context in requests |
| Sampling | Client-side model calls |
| Logging | Out-of-band logging |
Why “still works” misleads
Client-side compatibility is not symmetric. A client can drop support for a deprecated feature before your server does, so the feature “works” in your tests and fails in the client your customer actually uses. The test that matters is whether the feature is still in the spec, not whether it still returns 200.
A planning calendar
Put the window in the same planning doc as your roadmap. The migration guide covers the mechanics; the 60-second check tells you where you stand today. If the calendar says you are exposed and you would rather hand it off, the audit and migration service tracks the deprecation clock as part of the retainer.