Implement SEP-2577: Deprecate Roots, Sampling, and Logging

[felixweinberger]

This is a tracking issue for implementation of SEP-2577.

[mattzcarey]

Status — SEP-2577 (Deprecate Roots, Sampling, Logging)

Track: C — independent, starts now. Pure deprecation, no wire change.
Spec: seps/2577-deprecate-roots-sampling-and-logging.md · merged 2026-05-15

What's done

• Nothing in main. No @deprecated JSDoc on Server.createMessage, Server.listRoots, ctx.mcpReq.log, ctx.mcpReq.requestSampling, or the LoggingLevel type.
• Closed exploration: docs: @deprecated roots/sampling/logging (advisory; SEP-2577) #2071 — added @deprecated JSDoc to those four call sites. (+31/-2)

Outstanding (acceptance criteria, summary)

• R-2577-4 (sdk): Deprecated types carry @deprecated JSDoc (e.g. LoggingLevel, LoggingMessageNotification, CreateMessageRequest/Result, ListRootsRequest/Result)
• R-2577-5 (sdk): Union types unmodified — deprecated members STAY in ServerNotification/ClientRequest etc.
• R-2577-6 (wire): Deprecated capabilities MUST still be handled correctly (handle-but-warn) — top-level roots:{} still works, warning logged
• R-2577-8 (sdk): Clients and servers that still support the deprecated features SHOULD continue to declare the matching top-level capabilities during the deprecation window — i.e. SDK doesn't drop the capability advertisement just because it's deprecated
• R-2577-7 (guidance): 1-year removal floor for deprecated items
• R-2577-9 (guidance): New implementations SHOULD NOT add support for deprecated features unless needed for BC

Suggested phasing

1. Now: revive docs: @deprecated roots/sampling/logging (advisory; SEP-2577) #2071 against current main — pure JSDoc + a per-call warning (rate-limited / once-per-process) when a deprecated handler is registered or invoked.
2. Update the v1 → v2 migration guide (and README) with the migration suggestions from the changelog:
   • Roots → pass directories/files via tool parameters, resource URIs, or server configuration
   • Sampling → integrate directly with LLM provider APIs
   • Logging → stderr (stdio) or OpenTelemetry (overlap with Implement SEP-414: Document OpenTelemetry Trace Context Propagation Conventions #2196)
3. Add a doc check: README enumerates which features are deprecated, with timeline.

Related

• SEP-2596 (merged) is the deprecation policy (12-month minimum window). Process-only — no SDK code change. Doesn't need its own issue, but worth referencing in the docs PR.
• HTTP+SSE transport is independently reclassified Deprecated by SEP-2596 (already deprecated in spec since 2025-03-26); no new SDK action.

Coordination

• No dependencies. Independent.