This roadmap tracks the path to SEP-1730 Tier 1 for the Rust MCP SDK.
Spec 2025-11-25 (suite 0.1.16): Server 100% (30/30) · Client 100% (18/18) Spec 2026-07-28 (suite 0.2.0-alpha.9): Server 92.5% (37/40) · Client 75.0% (24/32)
All 2026-07-28 work carries the 2026-07-28 label and the
2026-07-28 spec milestone.
Per-scenario conformance status is tracked in the epic issue:
#977 — Tracking: 2026-07-28 spec conformance.
- Server: 3 scenarios (
tools-call-with-progressstateless behavior, SEP-2243 server-side custom headers, andserver-stateless— the SEP-2575 discovery/negotiation suite at 2/28 checks) - Client: 8 scenarios (SEP-2243 headers ×3,
request-metadata, and 4 single-check auth failures: SEP-2350 step-up, pre-registration, SEP-2352 AS migration, SEP-2468 issuer validation); fixes for SEP-2350 (#888) and SEP-2352 (#965) are already in review - CI: run the full
--spec-version 2026-07-28suites (stateless server) instead of hand-picked scenario lists; re-baseline on each draft-suite bump
Conformance alone does not cover the full spec surface. Feature work tracked via the milestone:
- SEP-2567 sessionless MCP via explicit state handles (#870)
- SEP-2260 server requests must associate with a client request (#873)
- SEP-2549 follow-up: client-side TTL-honoring cache (#974)
(SEP-2575 discovery & negotiation is covered by the server-stateless conformance scenario;
implementation is in review — #869, PRs #973, #943.)
The 2026-07-28 implementation ships as v3.0.0 (release PR #964): MRTR, SEP-2549 cache hints, SEP-2243 standard headers, and the SEP-2106 relaxations are merged but unreleased — tiering and relegation are evaluated against the latest stable release, so cutting v3.0.0 with the remaining conformance fixes is on the critical path. Migration guide (draft, kept current until release): discussion #969.
- Create
VERSIONING.md— document semver scheme, what constitutes a breaking change, and how breaking changes are communicated - Publish a dependency update policy (Tier 1 requires a published policy)
- Cut v3.0.0 (#964) including all conformance fixes (tier relegation is evaluated against the latest stable release)
- Tools — image results
- Tools — audio results
- Tools — embedded resources
- Prompts — embedded resources
- Prompts — image content
- Elicitation — URL mode
- Elicitation — default values
- Elicitation — complete notification
- Ping
- SSE transport — legacy (client)
- SSE transport — legacy (server)
- Pagination
- Protocol version negotiation
- JSON Schema 2020-12 support (upgrade from partial)
- Tools — error handling (add dedicated prose + example)
- Resources — reading binary (add dedicated example)
- Elicitation — form mode (add prose docs, not just example README)
- Elicitation — schema validation (add prose docs)
- Elicitation — enum values (add prose docs)
- Capability negotiation (add dedicated prose explaining the builder API)
- Protocol version negotiation (document version negotiation behavior)
- 2025-11-25 server conformance 100% (30 scenarios + pending
json-schema-2020-12,server-sse-polling) - 2025-11-25 client conformance 100% (18 scenarios + legacy
auth/2025-03-26-*) - SEP-2322 MRTR (14 server scenarios +
sep-2322-client-request-state) - SEP-2164 resource not found
- Cache hints (
caching) -
http-header-validation - Issue triage labels (bug, enhancement, needs confirmation, needs repro, ready for work, P0–P3)
These extension scenarios are tracked but do not count toward tier advancement:
| Scenario | Tag | Status |
|---|---|---|
auth/client-credentials-jwt |
extension | ❌ Failed — JWT aud claim verification error |
auth/client-credentials-basic |
extension | ✅ Passed |
auth/cross-app-access-complete-flow |
extension | ❌ Failed — sends authorization_code grant instead of jwt-bearer |
tasks-* |
extension | Not yet attempted |