The SDK tracks implementation of MCP spec components via GitHub Projects, with a dedicated project board for each spec revision. For example, see the 2025-11-25 spec revision board.

The current stable release line is 2.x (latest: 2.0.1, August 2026), implementing the 2025-11-25 MCP specification revision, including:

• Spec-accurate schema: enforced required fields with lenient wire deserialization, and a JSON compatibility foundation for forward/backward wire compatibility
• Enhanced schemas: JSON Schema 2020-12 validation of tool inputs and embedded schema documents (SEP-1613)
• Richer elicitation: client-side schema defaults (SEP-1034), URL mode elicitation (SEP-1036), form-based elicitation schemas
• Icons metadata (SEP-973): icons for tools, resources, resource templates, and prompts
• Streamable HTTP first: SSE transports deprecated in favor of Streamable HTTP
• Pluggable JSON serialization: Jackson 2 and Jackson 3 modules

2.x development continues with patch and minor releases for bug fixes, conformance improvements, and non-breaking features. See CHANGELOG.md for the release history.

The earlier 1.x and 0.x release lines receive security patches only — no feature or bug-fix backports. Users on those lines are encouraged to upgrade via the v2 migration guide.

The next major version, 3.x, will implement the 2026-07-28 MCP specification revision, including server/discover and the SEP-2575 stateless lifecycle. The first 3.0.0 milestone releases are planned for September 2026, tracked via a dedicated spec revision project board.

The Java SDK is an official Tier 2 SDK committed to full protocol support: new spec revisions are implemented within the Tier 2 six-month window, with conformance continuously verified against the MCP conformance suite in CI. Once caught up on the most recent specification revision, we aim for Tier 1: fully supporting new specification features on the day of their release.

Major version updates will align with MCP specification changes and breaking API changes as needed. The SDK is designed to evolve with the Java ecosystem, including:

• Virtual Threads and Structured Concurrency support
• Additional transport implementations
• Performance optimizations

Development is tracked via GitHub Issues and GitHub Projects.