📌 Summary

This PR introduces a major update to the rust-mcp-sdk crate, focusing on adding support for the latest MCP Protocol version (2025-11-25) while removing Cargo features for supporting older versions to simplify the codebase and reduce conditional feature flags.
The new protocol version is backward-compatible, ensuring a smoother transition. Additionally, numerous improvements have been made for cleaner code, better macro support, and enhanced functionality across the SDK.

These updates makes the SDK more robust, future-proof, and easier to maintain.

✨ Changes Made

• Protocol Update to 2025-11-25:
  • Added full support for the latest MCP schema, including new fields like icons,website_url in Implementation, and extended annotations/support for tools (e.g., execution).
  • Updated method signatures and params (e.g., CallToolRequestParams now includes meta and task; PaginatedRequestParams for listing tools/prompts/resources).
  • Renamed client methods for clarity and consistency (e.g., list_tools → request_tool_list, call_tool → request_tool_call, send_roots_list_changed → notify_roots_list_changed etc.).
  • Enhanced initialization with optional meta and richer server/client info (e.g., icons, descriptions).
• Removal of Legacy Version Support:
  • Eliminated Cargo features for older MCP versions (e.g., "2025_06_18", "2025_03_26", "2024_11_05") to streamline the code and remove conditional compilation. The SDK now defaults to the latest version, reducing complexity and maintenance overhead.
• Macro Enhancements:
  • Updated mcp_tool macro to support new attributes like icons (array of icon definitions with src, mime_type, sizes, theme), execution (for task support), and improved meta handling.
  • Introduced mcp_icon! macro for easy icon creation (used in examples and schema).
  • Refined mcp_elicit macro with support for "form" and "url" modes, including elicit_request_params and parsing from ElicitResultContent.
  • Version Bumps and Dependency Changes:
    • Bumped internal crate versions (e.g., rust-mcp-schema from 0.7.5 to 0.9.x).
• Handler and Runtime Updates:
  • Adjusted server/client handlers to use new param structs (e.g., Option for list requests).
  • Improved error handling and support for custom requests/notifications.
  • create_server() now accepts a McpServerHandler directly.
  • Introduced new traits to convert ServerHandler and ServerHandlerCore to a McpServerHandler.
    This enables the creation and configuration of handlers before calling the create_server().
• Examples and Documentation:
  • Updated all examples (e.g., hello-world-server, simple-mcp-client) to use new APIs, icons, and protocol features.
  • Added new assets like rust-mcp-icon.png and integrated it via mcp_icon!.
  • README updates for macros, with examples for mcp_tool and mcp_elicit.
• Other Improvements:
  • Removed unnecessary features, simplified conditional logic, and improved parsing/validation in macros.

⚠ BREAKING CHANGES:

• Older MCP version features are removed, users must update to the latest protocol.
• Method renames and param changes in client/server APIs may require code adjustments.
• Macro attributes have been expanded; check updated docs for compatibility.
• when calling create_server(), simply call .to_mcp_server_handler() on your handler instance to convert it to an McpServerHandler before passing it in:

- let server =  server_runtime::create_server(server_details, transport, handler);
+ let server =  server_runtime::create_server(server_details, transport, handler.to_mcp_server_handler());

🛠️ Testing Steps

💡 Additional Notes