diff --git a/packages/ai/src/parseTools.ts b/packages/ai/src/parseTools.ts
index fc8e00bf47..0e732cdb4a 100644
--- a/packages/ai/src/parseTools.ts
+++ b/packages/ai/src/parseTools.ts
@@ -1,4 +1,5 @@
 import type { VariableStore } from "@typebot.io/forge/types";
+import { safeStringify } from "@typebot.io/lib/safeStringify";
 import { isNotEmpty } from "@typebot.io/lib/utils";
 import { executeFunction } from "@typebot.io/variables/executeFunction";
 import type { Variable } from "@typebot.io/variables/schemas";
@@ -27,7 +28,7 @@ export const parseTools = ({
           body: tool.code!,
         });
         newVariables?.forEach((v) => variables.set(v.id, v.value));
-        return output;
+        return safeStringify(output) ?? "";
       },
     } satisfies CoreTool;
     return acc;
diff --git a/packages/forge/blocks/openai/src/actions/askAssistant.ts b/packages/forge/blocks/openai/src/actions/askAssistant.ts
index 0e4487f0bb..5608e3f18a 100644
--- a/packages/forge/blocks/openai/src/actions/askAssistant.ts
+++ b/packages/forge/blocks/openai/src/actions/askAssistant.ts
@@ -4,6 +4,7 @@ import type {
   LogsStore,
   VariableStore,
 } from "@typebot.io/forge/types";
+import { safeStringify } from "@typebot.io/lib/safeStringify";
 import { isDefined, isEmpty, isNotEmpty } from "@typebot.io/lib/utils";
 import { executeFunction } from "@typebot.io/variables/executeFunction";
 import { readDataStream } from "ai";
@@ -339,7 +340,7 @@ const createAssistantStream = async ({
 
                 return {
                   tool_call_id: toolCall.id,
-                  output,
+                  output: safeStringify(output) ?? "",
                 };
               },
             ),
diff --git a/packages/variables/src/executeFunction.ts b/packages/variables/src/executeFunction.ts
index dc7983929b..b41f824c0c 100644
--- a/packages/variables/src/executeFunction.ts
+++ b/packages/variables/src/executeFunction.ts
@@ -1,4 +1,3 @@
-import { safeStringify } from "@typebot.io/lib/safeStringify";
 import { stringifyError } from "@typebot.io/lib/stringifyError";
 import { isDefined } from "@typebot.io/lib/utils";
 import ivm from "isolated-vm";
@@ -74,9 +73,9 @@ export const executeFunction = async ({
     );
 
   try {
-    const output = await run(parsedBody);
+    const output: unknown = await run(parsedBody);
     return {
-      output: safeStringify(output) ?? "",
+      output,
       newVariables: Object.entries(updatedVariables)
         .map(([name, value]) => {
           const existingVariable = variables.find((v) => v.name === name);