v0.9.0

MCP Java SDK Release Notes

Breaking Changes ⚠️

There is one minor API breaking change that should not cause significant issues:

The type of the McpSchema.JSONRPCNotification params field has been changed from Map<String, Object> to Object.
This affects the signature of the sendNotification method in both McpClientSession and McpServerSession and
the signature of the notifyClients method in McpServerTransportProvider.

New Features

Transport Layer Enhancements

• Custom Context Paths: Enhanced HTTP Servlet SSE server transport to support deployment under non-root context paths (PR #112)

Server Configuration Improvements

• Server Instructions: Added support for setting server instructions, providing consistency with the Python SDK implementation (PR #99)

Developer Experience

• CallToolResult Enhancement: Added a constructor to CallToolResult that accepts a single String parameter for simpler API usage (PR #87)

Bug Fixes

Error Handling & Reliability

• Session Validation: Added error handling to return a 404 NOT_FOUND response when a request is made with a non-existent session ID (PR #138)
• Windows Compatibility: Fixed process startup issues when running tests on Windows systems (PR #85)

Refactoring & Technical Improvements

API Improvements

• Notification Parameters: Changed notification parameters type from Map<String,Object> to Object for more flexible parameter passing (PR #137)
• Refactored logging system to use exchange mechanism (PR #132)

Closed & Merged PRs Without Release Impact

• Various closed PRs related to HTTP protocol handling, typo fixes, and alternative implementations

Contributors

Special thanks to all contributors who helped improve the MCP Java SDK:

• @Aliaksie (Aliaksei)
• @tzolov (Christian Tzolov)
• @chemicL (Dariusz Jędrzejczyk)
• @EvanMi
• @noear (西东)
• @codezjx
• @codeboyzh (codeboyzz)
• @denniskawurek (Dennis Kawurek)

This release includes enhancements to transport mechanisms, improved server configuration options, better cross-platform compatibility, and various other improvements to the MCP Java SDK.