diff --git a/adk/common/tool/follow_up_tool.go b/adk/common/tool/follow_up_tool.go
index bc6f292..8c11fd5 100644
--- a/adk/common/tool/follow_up_tool.go
+++ b/adk/common/tool/follow_up_tool.go
@@ -37,7 +37,7 @@ func (fi *FollowUpInfo) String() string {
 	var sb strings.Builder
 	sb.WriteString("We need more information. Please answer the following questions:\n")
 	for i, q := range fi.Questions {
-		sb.WriteString(fmt.Sprintf("%d. %s\n", i+1, q))
+		_, _ = fmt.Fprintf(&sb, "%d. %s\n", i+1, q)
 	}
 	return sb.String()
 }
diff --git a/adk/multiagent/deep/utils/utils.go b/adk/multiagent/deep/utils/utils.go
index 984056e..af438c3 100644
--- a/adk/multiagent/deep/utils/utils.go
+++ b/adk/multiagent/deep/utils/utils.go
@@ -111,7 +111,7 @@ func GetSessionValue[T any](ctx context.Context, key string) (T, bool) {
 func FormatExecutedSteps(in []planexecute.ExecutedStep) string {
 	var sb strings.Builder
 	for idx, m := range in {
-		sb.WriteString(fmt.Sprintf("## %d. Step: %v\n  Result: %v\n\n", idx+1, m.Step, m.Result))
+		_, _ = fmt.Fprintf(&sb, "## %d. Step: %v\n  Result: %v\n\n", idx+1, m.Step, m.Result)
 	}
 	return sb.String()
 }
diff --git a/adk/multiagent/integration-excel-agent/utils/utils.go b/adk/multiagent/integration-excel-agent/utils/utils.go
index 984056e..af438c3 100644
--- a/adk/multiagent/integration-excel-agent/utils/utils.go
+++ b/adk/multiagent/integration-excel-agent/utils/utils.go
@@ -111,7 +111,7 @@ func GetSessionValue[T any](ctx context.Context, key string) (T, bool) {
 func FormatExecutedSteps(in []planexecute.ExecutedStep) string {
 	var sb strings.Builder
 	for idx, m := range in {
-		sb.WriteString(fmt.Sprintf("## %d. Step: %v\n  Result: %v\n\n", idx+1, m.Step, m.Result))
+		_, _ = fmt.Fprintf(&sb, "## %d. Step: %v\n  Result: %v\n\n", idx+1, m.Step, m.Result)
 	}
 	return sb.String()
 }