We're pleased to announce Spring AI MCP 0.4.0 milestone release.

Repository Configuration

Add this Spring milestone repository to your POM:

<repositories>
  <repository>
    <id>spring-milestones</id>
    <name>Spring Milestones</name>
    <url>https://repo.spring.io/libs-milestone-local</url>
    <snapshots>
      <enabled>false</enabled>
    </snapshots>
  </repository>
</repositories>

Major Features

Reference documentation: https://docs.spring.io/spring-ai-mcp/reference/overview.html

Enhanced Roots Management

• Implemented proper ListRootsResult wrapping in async client
• Added listRoots methods in server components
• Implemented roots change notification handling in async server
• Added roots integration tests including async notifications
• Added support for roots change notification with single and multiple consumers
• Improved robustness of root addition/removal scenarios

Improved Architecture & Documentation

• Introduced ClientMcpTransport and ServerMcpTransport marker interfaces
• Updated client/server implementations with appropriate transport interfaces
• Reorganized documentation structure for better clarity
• Relocated documentation images to mcp-docs/antora directory
• Updated README files with links to online documentation

Server-Side Capabilities

• Added createMessage method to McpAsyncServer and McpSyncServer for LLM sampling
• Implemented client-side sampling features in the Model Context Protocol (MCP) server
• Enhanced server info implementation with default builder options

Bug Fixes & Improvements

• Fixed potential NullPointerException in toolsListRequestHandler when handling null params
• Improved error handling for uninitialized clients and missing capabilities
• Enhanced test coverage across multiple components

Technical Improvements

• Added structured logging support with configurable severity levels (DEBUG to EMERGENCY)
• Implemented logging message notifications
• Added logging consumers for client-side log handling
• Extended test coverage for logging functionality

Notes

• Documentation has been updated to reflect new features and improvements
• Several architectural improvements have been made to enhance maintainability