diff --git a/contributing/samples/tools/parallel_functions/tests/test_all_tools.json b/contributing/samples/tools/parallel_functions/tests/test_all_tools.json
index 3d5c7875..4b6caece 100644
--- a/contributing/samples/tools/parallel_functions/tests/test_all_tools.json
+++ b/contributing/samples/tools/parallel_functions/tests/test_all_tools.json
@@ -193,4 +193,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/contributing/samples/tools/parallel_functions/tests/test_parallel_mixed.json b/contributing/samples/tools/parallel_functions/tests/test_parallel_mixed.json
index e4bb7191..1fa993e3 100644
--- a/contributing/samples/tools/parallel_functions/tests/test_parallel_mixed.json
+++ b/contributing/samples/tools/parallel_functions/tests/test_parallel_mixed.json
@@ -125,4 +125,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/contributing/samples/tools/parallel_functions/tests/test_parallel_weather.json b/contributing/samples/tools/parallel_functions/tests/test_parallel_weather.json
index 7c8e4b7d..660e754e 100644
--- a/contributing/samples/tools/parallel_functions/tests/test_parallel_weather.json
+++ b/contributing/samples/tools/parallel_functions/tests/test_parallel_weather.json
@@ -126,4 +126,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/contributing/samples/tools/pydantic_argument/tests/test_create_company.json b/contributing/samples/tools/pydantic_argument/tests/test_create_company.json
index 0d6909f9..5b9d2278 100644
--- a/contributing/samples/tools/pydantic_argument/tests/test_create_company.json
+++ b/contributing/samples/tools/pydantic_argument/tests/test_create_company.json
@@ -136,4 +136,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/contributing/samples/tools/pydantic_argument/tests/test_create_user.json b/contributing/samples/tools/pydantic_argument/tests/test_create_user.json
index 37452017..ce1ae1b3 100644
--- a/contributing/samples/tools/pydantic_argument/tests/test_create_user.json
+++ b/contributing/samples/tools/pydantic_argument/tests/test_create_user.json
@@ -101,4 +101,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/contributing/samples/tools/pydantic_argument/tests/test_create_user_with_prefs.json b/contributing/samples/tools/pydantic_argument/tests/test_create_user_with_prefs.json
index 37e52b5d..a5e9969b 100644
--- a/contributing/samples/tools/pydantic_argument/tests/test_create_user_with_prefs.json
+++ b/contributing/samples/tools/pydantic_argument/tests/test_create_user_with_prefs.json
@@ -104,4 +104,4 @@
       }
     }
   ]
-}
\ No newline at end of file
+}
diff --git a/src/google/adk/cli/agent_test_runner.py b/src/google/adk/cli/agent_test_runner.py
index 763c35de..aca43111 100644
--- a/src/google/adk/cli/agent_test_runner.py
+++ b/src/google/adk/cli/agent_test_runner.py
@@ -881,6 +881,7 @@ def rebuild_tests(path: str):
       # Write back to file
       with open(test_file, "w") as f:
         json.dump(session_data, f, indent=2, sort_keys=True)
+        f.write("\n")
 
       print(f"Successfully rebuilt {test_file}")