diff --git a/mcp-client-ruby/client.rb b/mcp-client-ruby/client.rb
index e72a24d5..60ac772a 100644
--- a/mcp-client-ruby/client.rb
+++ b/mcp-client-ruby/client.rb
@@ -6,7 +6,7 @@
 require "mcp"
 
 class MCPClient
-  ANTHROPIC_MODEL = "claude-sonnet-4-5"
+  ANTHROPIC_MODEL = "claude-sonnet-5"
 
   def initialize
     @mcp_client = nil