diff --git a/src/agentic.ts b/src/agentic.ts
index 8cd94fc..0f91442 100644
--- a/src/agentic.ts
+++ b/src/agentic.ts
@@ -56,12 +56,12 @@ export class Agentic {
       new HumanFeedbackMechanismCLI({ agentic: this })
   }
 
-  public get openai(): types.openai.OpenAIClient {
-    return this._openai!
+  public get openai(): types.openai.OpenAIClient | undefined {
+    return this._openai
   }
 
-  public get anthropic(): types.anthropic.Client {
-    return this._anthropic!
+  public get anthropic(): types.anthropic.Client | undefined {
+    return this._anthropic
   }
 
   public get defaultHumanFeedbackMechamism() {
diff --git a/src/anthropic.ts b/src/anthropic.ts
index b0ca8f6..b1dd008 100644
--- a/src/anthropic.ts
+++ b/src/anthropic.ts
@@ -38,7 +38,13 @@ export class AnthropicChatModel<
       ...options
     })
 
-    this._client = this._agentic.anthropic
+    if (this._agentic.anthropic) {
+      this._client = this._agentic.anthropic
+    } else {
+      throw new Error(
+        'AnthropicChatModel requires an Anthropic client to be configured on the Agentic runtime'
+      )
+    }
   }
 
   protected override async _createChatCompletion(
diff --git a/src/openai.ts b/src/openai.ts
index d37cdef..9785341 100644
--- a/src/openai.ts
+++ b/src/openai.ts
@@ -29,7 +29,13 @@ export class OpenAIChatModel<
       ...options
     })
 
-    this._client = this._agentic.openai
+    if (this._agentic.openai) {
+      this._client = this._agentic.openai
+    } else {
+      throw new Error(
+        'OpenAIChatModel requires an OpenAI client to be configured on the Agentic runtime'
+      )
+    }
   }
 
   protected override async _createChatCompletion(