diff --git a/haystack_experimental/components/generators/chat/openai.py b/haystack_experimental/components/generators/chat/openai.py
index f7a028f3..7517d508 100644
--- a/haystack_experimental/components/generators/chat/openai.py
+++ b/haystack_experimental/components/generators/chat/openai.py
@@ -55,7 +55,8 @@ def _convert_message_to_openai_format(message: ChatMessage) -> Dict[str, Any]:
                 {
                     "id": tc.id,
                     "type": "function",
-                    "function": {"name": tc.tool_name, "arguments": json.dumps(tc.arguments)},
+                    # We disable ensure_ascii so special chars like emojis are not converted
+                    "function": {"name": tc.tool_name, "arguments": json.dumps(tc.arguments, ensure_ascii=False)},
                 }
             )
         openai_msg["tool_calls"] = openai_tool_calls
diff --git a/haystack_experimental/components/tools/openai/function_caller.py b/haystack_experimental/components/tools/openai/function_caller.py
index 0c12b963..c4e1a573 100644
--- a/haystack_experimental/components/tools/openai/function_caller.py
+++ b/haystack_experimental/components/tools/openai/function_caller.py
@@ -87,8 +87,9 @@ def run(self, messages: List[ChatMessage]):
                     try:
                         function_response = function_to_call(**function_args)
                         messages.append(
+                            # We disable ensure_ascii so special chars like emojis are not converted
                             ChatMessage.from_function(
-                                content=json.dumps(function_response),
+                                content=json.dumps(function_response, ensure_ascii=False),
                                 name=function_name,
                             )
                         )
diff --git a/haystack_experimental/components/tools/openapi/openapi_tool.py b/haystack_experimental/components/tools/openapi/openapi_tool.py
index 7bcb80d5..9c9b33a2 100644
--- a/haystack_experimental/components/tools/openapi/openapi_tool.py
+++ b/haystack_experimental/components/tools/openapi/openapi_tool.py
@@ -172,7 +172,8 @@ def run(
         except Exception as e:  # pylint: disable=broad-exception-caught
             logger.error("Error invoking OpenAPI endpoint. Error: {e}", e=str(e))
             service_response = {"error": str(e)}
-        response_messages = [ChatMessage.from_user(json.dumps(service_response))]
+        # We disable ensure_ascii so special chars like emojis are not converted
+        response_messages = [ChatMessage.from_user(json.dumps(service_response, ensure_ascii=False))]
 
         return {"service_response": response_messages}
 
diff --git a/haystack_experimental/components/tools/tool_invoker.py b/haystack_experimental/components/tools/tool_invoker.py
index 08156605..14e7ffe3 100644
--- a/haystack_experimental/components/tools/tool_invoker.py
+++ b/haystack_experimental/components/tools/tool_invoker.py
@@ -145,7 +145,8 @@ def _prepare_tool_result_message(self, result: Any, tool_call: ToolCall) -> Chat
 
         if self.convert_result_to_json_string:
             try:
-                tool_result_str = json.dumps(result)
+                # We disable ensure_ascii so special chars like emojis are not converted
+                tool_result_str = json.dumps(result, ensure_ascii=False)
             except Exception as e:
                 if self.raise_on_failure:
                     raise StringConversionError("Failed to convert tool result to string using `json.dumps`") from e