diff --git a/supabase_functions/_async/functions_client.py b/supabase_functions/_async/functions_client.py
index 4a037f9..aa66842 100644
--- a/supabase_functions/_async/functions_client.py
+++ b/supabase_functions/_async/functions_client.py
@@ -3,7 +3,7 @@
 from httpx import HTTPError, Response
 
 from ..errors import FunctionsHttpError, FunctionsRelayError
-from ..utils import AsyncClient
+from ..utils import AsyncClient, is_http_url, is_valid_str_arg
 from ..version import __version__
 
 
@@ -16,6 +16,8 @@ def __init__(
         verify: bool = True,
         proxy: Optional[str] = None,
     ):
+        if not is_http_url(url):
+            ValueError("url must be a valid HTTP URL string")
         self.url = url
         self.headers = {
             "User-Agent": f"supabase-py/functions-py v{__version__}",
@@ -25,7 +27,7 @@ def __init__(
             base_url=self.url,
             headers=self.headers,
             verify=bool(verify),
-            timeout=timeout,
+            timeout=int(abs(timeout)),
             proxy=proxy,
             follow_redirects=True,
             http2=True,
@@ -73,6 +75,8 @@ async def invoke(
             `body`: the body of the request
             `responseType`: how the response should be parsed. The default is `json`
         """
+        if not is_valid_str_arg(function_name):
+            raise ValueError("function_name must a valid string value.")
         headers = self.headers
         body = None
         response_type = "text/plain"
diff --git a/supabase_functions/_sync/functions_client.py b/supabase_functions/_sync/functions_client.py
index 3550219..b407a5f 100644
--- a/supabase_functions/_sync/functions_client.py
+++ b/supabase_functions/_sync/functions_client.py
@@ -3,7 +3,7 @@
 from httpx import HTTPError, Response
 
 from ..errors import FunctionsHttpError, FunctionsRelayError
-from ..utils import SyncClient
+from ..utils import SyncClient, is_http_url, is_valid_str_arg
 from ..version import __version__
 
 
@@ -16,6 +16,8 @@ def __init__(
         verify: bool = True,
         proxy: Optional[str] = None,
     ):
+        if not is_http_url(url):
+            ValueError("url must be a valid HTTP URL string")
         self.url = url
         self.headers = {
             "User-Agent": f"supabase-py/functions-py v{__version__}",
@@ -25,7 +27,7 @@ def __init__(
             base_url=self.url,
             headers=self.headers,
             verify=bool(verify),
-            timeout=timeout,
+            timeout=int(abs(timeout)),
             proxy=proxy,
             follow_redirects=True,
             http2=True,
@@ -73,6 +75,8 @@ def invoke(
             `body`: the body of the request
             `responseType`: how the response should be parsed. The default is `json`
         """
+        if not is_valid_str_arg(function_name):
+            raise ValueError("function_name must a valid string value.")
         headers = self.headers
         body = None
         response_type = "text/plain"
diff --git a/supabase_functions/utils.py b/supabase_functions/utils.py
index 46005dc..1f8b969 100644
--- a/supabase_functions/utils.py
+++ b/supabase_functions/utils.py
@@ -1,3 +1,5 @@
+from urllib.parse import urlparse
+
 from httpx import AsyncClient as AsyncClient  # noqa: F401
 from httpx import Client as BaseClient
 
@@ -7,3 +9,11 @@
 class SyncClient(BaseClient):
     def aclose(self) -> None:
         self.close()
+
+
+def is_valid_str_arg(target: str) -> bool:
+    return isinstance(target, str) and len(target.strip()) > 0
+
+
+def is_http_url(url: str) -> bool:
+    return urlparse(url).scheme in {"https", "http"}