1 files changed, 19 insertions, 3 deletions
diff --git a/pkg/aflow/schema.go b/pkg/aflow/schema.go
index e34d465ea..2b2d77f76 100644
--- a/pkg/aflow/schema.go
+++ b/pkg/aflow/schema.go
@@ -54,13 +54,19 @@ func convertToMap[T any](val T) map[string]any {
 // convertFromMap converts an untyped map to a struct.
 // It always ensures that all struct fields are present in the map.
 // In the strict mode it also checks that the map does not contain any other unused elements.
-func convertFromMap[T any](m map[string]any, strict bool) (T, error) {
+// If tool is set, return errors in the form suitable to return back to LLM
+// during tool arguments conversion.
+func convertFromMap[T any](m map[string]any, strict, tool bool) (T, error) {
 	m = maps.Clone(m)
 	var val T
 	for name, field := range foreachField(&val) {
 		f, ok := m[name]
 		if !ok {
-			return val, fmt.Errorf("field %v is not present when converting map to %T", name, val)
+			if tool {
+				return val, &toolArgsError{fmt.Errorf("missing argument %q", name)}
+			} else {
+				return val, fmt.Errorf("field %q is not present when converting map to %T", name, val)
+			}
 		}
 		delete(m, name)
 		if mm, ok := f.(map[string]any); ok && field.Type() == reflect.TypeFor[json.RawMessage]() {
@@ -69,8 +75,16 @@ func convertFromMap[T any](m map[string]any, strict bool) (T, error) {
 				return val, err
 			}
 			field.Set(reflect.ValueOf(json.RawMessage(raw)))
-		} else {
+		} else if field.Type() == reflect.TypeOf(f) {
 			field.Set(reflect.ValueOf(f))
+		} else {
+			if tool {
+				return val, &toolArgsError{fmt.Errorf("argument %q has wrong type: got %T, want %v",
+					name, f, field.Type().Name())}
+			} else {
+				return val, fmt.Errorf("field %q has wrong type: got %T, want %v",
+					name, f, field.Type().Name())
+			}
 		}
 	}
 	if strict && len(m) != 0 {
@@ -79,6 +93,8 @@ func convertFromMap[T any](m map[string]any, strict bool) (T, error) {
 	return val, nil
 }
 
+type toolArgsError struct{ error }
+
 // foreachField iterates over all public fields of the struct provided in data.
 func foreachField(data any) iter.Seq2[string, reflect.Value] {
 	return func(yield func(string, reflect.Value) bool) {