Deprecated Features
This page is the registry of specification features that are currently in the Deprecated state under the feature lifecycle and deprecation policy (SEP-2596).
A Deprecated feature remains part of the specification but is scheduled for removal: new implementations SHOULD NOT adopt it, and existing implementations SHOULD migrate before the feature’s earliest removal. The earliest removal marks when a feature becomes eligible for removal; the actual removal is a Core Maintainer decision taken during release preparation and may happen later.
This registry is a derived view kept consistent with the per-feature deprecation notices and changelog entries, which are the normative records.
Deprecated
| Feature | Deprecation SEP | Deprecated in | Migration path | Earliest removal |
|---|---|---|---|---|
| Roots | SEP-2577 | 2026-07-28 | Pass directories or files via tool parameters, resource URIs, or server configuration | First revision released on or after 2027-07-28 |
| Sampling | SEP-2577 | 2026-07-28 | Integrate directly with LLM provider APIs | First revision released on or after 2027-07-28 |
| Logging | SEP-2577 | 2026-07-28 | Log to stderr for stdio transports; use OpenTelemetry for observability | First revision released on or after 2027-07-28 |
| Dynamic Client Registration | PR #2858 | 2026-07-28 | Client ID Metadata Documents | First revision released on or after 2027-07-28 |
includeContext: "thisServer" / "allServers" (Sampling) | SEP-2596 | 2025-11-25 | Omit the field or use "none" | Follows Sampling (SEP-2577) |
| HTTP+SSE transport | SEP-2596 | 2025-03-26 | Streamable HTTP | Three months after SEP-2596 reaches Final |
The HTTP+SSE transport and the includeContext values were already described
as deprecated before the lifecycle policy existed; SEP-2596 reclassifies them
as Deprecated under its transition provisions.
Removed
No features have been removed under this policy yet. When a Deprecated feature is removed, its row moves to this section with a link to the changelog entry recording the removal.