fix(test): skip serialize tool's annotation if empty (#160)

* fix(test): skip serialize tool's annotation if empty

1. skip serialize tool's annotation if empty
2. close js server and client when close

* fix(test): fix test with js, don't close too early

crates/rmcp/tests/test_with_js/server.js

@@ -32,4 +32,4 @@ server.tool(
 );
 
 const transport = new StdioServerTransport();
-await server.connect(transport);
+await server.connect(transport);