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.