diff --git a/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.test.ts b/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.test.ts
index 2456499b2d66f..199a6d8f1cbca 100644
--- a/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.test.ts
+++ b/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.test.ts
@@ -329,8 +329,8 @@ describe('Observability AI Assistant client', () => {
               { role: 'user', content: 'How many alerts do I have?' },
             ]),
             functionCalling: 'native',
-            toolChoice: 'auto',
-            tools: {},
+            toolChoice: undefined,
+            tools: undefined,
           },
         ]);
       });
@@ -1373,7 +1373,7 @@ describe('Observability AI Assistant client', () => {
 
       expect(Object.keys(firstBody.tools ?? {}).length).toEqual(1);
 
-      expect(body.tools).toEqual({});
+      expect(body.tools).toEqual(undefined);
     });
   });
 
diff --git a/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.ts b/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.ts
index c03f7d6333825..8d1ee6138e54f 100644
--- a/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.ts
+++ b/x-pack/platform/plugins/shared/observability_solution/observability_ai_assistant/server/service/client/index.ts
@@ -481,13 +481,24 @@ export class ObservabilityAIAssistantClient {
       tracer: LangTracer;
     }
   ): Observable<ChatCompletionChunkEvent | TokenCountEvent | ChatCompletionMessageEvent> => {
-    const tools = functions?.reduce((acc, fn) => {
-      acc[fn.name] = {
-        description: fn.description,
-        schema: fn.parameters,
-      };
-      return acc;
-    }, {} as Record<string, { description: string; schema: any }>);
+    let tools: Record<string, { description: string; schema: any }> | undefined;
+    let toolChoice: ToolChoiceType | { function: string } | undefined;
+
+    if (functions?.length) {
+      tools = functions.reduce((acc, fn) => {
+        acc[fn.name] = {
+          description: fn.description,
+          schema: fn.parameters,
+        };
+        return acc;
+      }, {} as Record<string, { description: string; schema: any }>);
+
+      toolChoice = functionCall
+        ? {
+            function: functionCall,
+          }
+        : ToolChoiceType.auto;
+    }
 
     const chatComplete$ = defer(() =>
       this.dependencies.inferenceClient.chatComplete({
@@ -497,11 +508,7 @@ export class ObservabilityAIAssistantClient {
           messages.filter((message) => message.message.role !== MessageRole.System)
         ),
         functionCalling: simulateFunctionCalling ? 'simulated' : 'native',
-        toolChoice: functionCall
-          ? {
-              function: functionCall,
-            }
-          : ToolChoiceType.auto,
+        toolChoice,
         tools,
       })
     ).pipe(