diff --git a/camel/agents/chat_agent.py b/camel/agents/chat_agent.py
index 805df53cb4..e54937ab53 100644
--- a/camel/agents/chat_agent.py
+++ b/camel/agents/chat_agent.py
@@ -643,7 +643,7 @@ def step_tool_call(
         func = self.func_dict[func_name]
 
         args_str: str = choice.message.tool_calls[0].function.arguments
-        args = json.loads(args_str.replace("'", "\""))
+        args = json.loads(args_str)
 
         # Pass the extracted arguments to the indicated function
         try:
@@ -702,7 +702,7 @@ async def step_tool_call_async(
         func = self.func_dict[func_name]
 
         args_str: str = choice.message.tool_calls[0].function.arguments
-        args = json.loads(args_str.replace("'", "\""))
+        args = json.loads(args_str)
 
         # Pass the extracted arguments to the indicated function
         try:
diff --git a/camel/functions/open_api_function.py b/camel/functions/open_api_function.py
index b4211553b2..bf77829e24 100644
--- a/camel/functions/open_api_function.py
+++ b/camel/functions/open_api_function.py
@@ -13,16 +13,15 @@
 # =========== Copyright 2023 @ CAMEL-AI.org. All Rights Reserved. ===========
 import json
 import os
-from typing import Any, Callable, Dict, List, Tuple
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
-import prance
 import requests
 
 from camel.functions import OpenAIFunction, openapi_security_config
 from camel.types import OpenAPIName
 
 
-def parse_openapi_file(openapi_spec_path: str) -> Dict[str, Any]:
+def parse_openapi_file(openapi_spec_path: str) -> Optional[Dict[str, Any]]:
     r"""Load and parse an OpenAPI specification file.
 
     This function utilizes the `prance.ResolvingParser` to parse and resolve
@@ -34,8 +33,14 @@ def parse_openapi_file(openapi_spec_path: str) -> Dict[str, Any]:
             specification.
 
     Returns:
-        Dict[str, Any]: The parsed OpenAPI specification as a dictionary.
+        Optional[Dict[str, Any]]: The parsed OpenAPI specification
+            as a dictionary. :obj:`None` if the package is not installed.
     """
+    try:
+        import prance
+    except Exception:
+        return None
+
     # Load the OpenAPI spec
     parser = prance.ResolvingParser(
         openapi_spec_path, backend="openapi-spec-validator", strict=False
@@ -451,6 +456,8 @@ def apinames_filepaths_to_funs_schemas(
         )
 
         openapi_spec = parse_openapi_file(file_path)
+        if openapi_spec is None:
+            return [], []
 
         # Generate and merge function schemas
         openapi_functions_schemas = openapi_spec_to_openai_schemas(
diff --git a/camel/functions/slack_functions.py b/camel/functions/slack_functions.py
index 114cc30572..bf2e58abae 100644
--- a/camel/functions/slack_functions.py
+++ b/camel/functions/slack_functions.py
@@ -24,8 +24,6 @@
 
     from slack_sdk import WebClient
 
-from slack_sdk.errors import SlackApiError
-
 from camel.functions import OpenAIFunction
 
 logger = logging.getLogger(__name__)
@@ -89,6 +87,8 @@ def create_slack_channel(name: str, is_private: Optional[bool] = True) -> str:
         SlackApiError: If there is an error during get slack channel
             information.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         response = slack_client.conversations_create(
@@ -115,6 +115,8 @@ def join_slack_channel(channel_id: str) -> str:
         SlackApiError: If there is an error during get slack channel
             information.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         response = slack_client.conversations_join(channel=channel_id)
@@ -137,6 +139,8 @@ def leave_slack_channel(channel_id: str) -> str:
         SlackApiError: If there is an error during get slack channel
             information.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         response = slack_client.conversations_leave(channel=channel_id)
@@ -155,6 +159,8 @@ def get_slack_channel_information() -> str:
         SlackApiError: If there is an error during get slack channel
             information.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         response = slack_client.conversations_list()
@@ -189,6 +195,8 @@ def get_slack_channel_message(channel_id: str) -> str:
     Raises:
         SlackApiError: If there is an error during get slack channel message.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         result = slack_client.conversations_history(channel=channel_id)
@@ -222,6 +230,8 @@ def send_slack_message(
     Raises:
         SlackApiError: If an error occurs while sending the message.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         if user:
@@ -254,6 +264,8 @@ def delete_slack_message(
     Raises:
         SlackApiError: If an error occurs while sending the message.
     """
+    from slack_sdk.errors import SlackApiError
+
     try:
         slack_client = _login_slack()
         response = slack_client.chat_delete(channel=channel_id, ts=time_stamp)