- Expose mcp_protocol from mcp-server for reuse in tests and callers. - In MessageProcessor, detect structured ToolCallRequestParams in tools/call and forward to a new handler. - Add handle_new_tool_calls scaffold (returns error for now). - Test helper: add send_send_user_message_tool_call to McpProcess to send ConversationSendMessage requests; This is the second PR in a stack. Stack: Final: #1686 Intermediate: #1751 First: #1750