fix(tests): replace serde_json::from_str with serde_yaml::from_str for tool output assertions

server/src/handlers/graph.rs

@@ -1643,7 +1643,7 @@ mod tests {
             .execute(json!({"limit": 1, "offset": 0}), state.clone())
             .await
             .unwrap();
-        let parsed_paged: serde_json::Value = serde_json::from_str(&paged_res).unwrap();
+        let parsed_paged: serde_json::Value = serde_yaml::from_str(&paged_res).unwrap();
         assert_eq!(parsed_paged["total_count"], 2);
         assert_eq!(parsed_paged["has_more"], true);
     }