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/src/model/tool.rs

@@ -18,6 +18,7 @@ pub struct Tool {
     pub description: Option<Cow<'static, str>>,
     /// A JSON Schema object defining the expected parameters for the tool
     pub input_schema: Arc<JsonObject>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     /// Optional additional tool information.
     pub annotations: Option<ToolAnnotations>,
 }