diff --git a/simplemind/providers/anthropic.py b/simplemind/providers/anthropic.py
index e4cdb7a..328577f 100644
--- a/simplemind/providers/anthropic.py
+++ b/simplemind/providers/anthropic.py
@@ -21,6 +21,8 @@ class Anthropic(BaseProvider):
     @property
     def client(self):
         """The raw Anthropic client."""
+        if not self.api_key:
+            raise ValueError("Anthropic API key is required")
         return anthropic.Anthropic(api_key=self.api_key)
 
     @property
diff --git a/simplemind/providers/groq.py b/simplemind/providers/groq.py
index 465f428..ec5e6ac 100644
--- a/simplemind/providers/groq.py
+++ b/simplemind/providers/groq.py
@@ -20,6 +20,8 @@ class Groq(BaseProvider):
     @property
     def client(self):
         """The raw Groq client."""
+        if not self.api_key:
+            raise ValueError("Groq API key is required")
         return groq.Groq(api_key=self.api_key)
 
     @property
@@ -43,7 +45,7 @@ class Groq(BaseProvider):
         # Create and return a properly formatted Message instance
         return Message(
             role="assistant",
-            text=assistant_message.content,
+            text=assistant_message.content or "",
             raw=response,
             llm_model=conversation.llm_model or DEFAULT_MODEL,
             llm_provider=PROVIDER_NAME,
diff --git a/simplemind/providers/openai.py b/simplemind/providers/openai.py
index 4eb2795..2006f0c 100644
--- a/simplemind/providers/openai.py
+++ b/simplemind/providers/openai.py
@@ -20,6 +20,8 @@ class OpenAI(BaseProvider):
     @property
     def client(self):
         """The raw OpenAI client."""
+        if not self.api_key:
+            raise ValueError("OpenAI API key is required")
         return oa.OpenAI(api_key=self.api_key)
 
     @property
diff --git a/simplemind/providers/xai.py b/simplemind/providers/xai.py
index 04b9709..df4cc92 100644
--- a/simplemind/providers/xai.py
+++ b/simplemind/providers/xai.py
@@ -22,10 +22,11 @@ class XAI(BaseProvider):
     @property
     def client(self):
         """The raw OpenAI client."""
-
+        if not self.api_key:
+            raise ValueError("XAI API key is required")
         return oa.OpenAI(
-            api_key=settings.XAI_API_KEY,
-            base_url="https://api.x.ai/v1",
+            api_key=self.api_key,
+            base_url=BASE_URL,
         )
 
     @property