We're pleased to announce Spring AI MCP 0.6.0 milestone release.

Breaking Changes ⚠️

• McpClient.using() - Use McpClient.sync() or McpClient.async() instead
• McpServer.using() - Use McpServer.sync() or McpServer.async() instead
• McpServer.ToolRegistration - Use McpServerFeatures.SyncToolRegistration or McpServerFeatures.AsyncToolRegistration instead
• McpServer.ResourceRegistration - Use McpServerFeatures.SyncResourceRegistration or McpServerFeatures.AsyncResourceRegistration instead
• McpServer.PromptRegistration - Use McpServerFeatures.SyncPromptRegistration or McpServerFeatures.AsyncPromptRegistration instead
• ToolHelper.toToolRegistration() - Use ToolHelper.toSyncToolRegistration() instead

Follow the 0.6.0 Migration Guide for the new API changes.

Major Features & Improvements

Protocol Version Negotiation

• Implemented protocol version negotiation between MCP client and server
• Added support for multiple protocol versions in both client and server
• Implemented fallback mechanism to latest version when unsupported version requested
• Added comprehensive test coverage for version negotiation

Configurable SSE Endpoints

• Made SSE endpoint path configurable in server transports
• Added customization support for WebFluxSseServerTransport, WebMvcSseServerTransport, and HttpServletSseServerTransport
• Maintained backward compatibility with default "/sse" endpoint
• Aligned Java SDK behavior with Python SDK's SseServerTransport

Bug Fixes 🐛

Transport Layer Improvements

• Added cleanup logic for inbound processing in transport layer
• Enhanced transport reliability and resource management

Improvements & Refactoring 🔧

API Refactoring

• Separated asynchronous and synchronous client interactions
• Introduced new client creation patterns:

  // Synchronous client API
  McpClient.sync(transport).build();
  
  // Asynchronous client API
  McpClient.async(transport).build();
  

• Made RequestHandler type-aware of responses
• Deprecated legacy client builder patterns

Code Quality & Structure

• Aligned abstract tests in mcp-test with mcp-core
• Improved method scope definitions
• Enhanced code organization and maintainability