diff --git a/js/ai/src/generate/response.ts b/js/ai/src/generate/response.ts
index 54fcb7c1b7..d6631e7e5b 100644
--- a/js/ai/src/generate/response.ts
+++ b/js/ai/src/generate/response.ts
@@ -93,6 +93,13 @@ export class GenerateResponse<O = unknown> implements ModelResponseData {
       );
     }
 
+    if (this.finishReason === 'length') {
+      throw new GenerationResponseError(
+        this,
+        `Model generated a message that is too long. Finish reason: '${this.finishReason}': ${this.finishMessage}`
+      );
+    }
+
     if (!this.message && !this.operation) {
       throw new GenerationResponseError(
         this,