diff --git a/src/routes/transcribe.js b/src/routes/transcribe.js
index 7b0e565..5c845be 100644
--- a/src/routes/transcribe.js
+++ b/src/routes/transcribe.js
@@ -79,9 +79,8 @@ router.post('/transcribe', authMiddleware, upload.single('audio'), async (req, r
         contentType: req.file.mimetype || 'audio/webm'
       });
       form.append('model', sttModel);
-      form.append('language', 'en');
-      form.append('response_format', 'json');
-      form.append('prompt', 'Medical patient encounter. Pediatric. Clinical terms, diagnoses, medications.');
+      // Note: Vertex AI Chirp via LiteLLM does not support 'prompt' or 'response_format'
+      // Only send parameters Chirp actually accepts
       var sttHeaders = Object.assign({}, form.getHeaders());
       if (process.env.LITELLM_API_KEY) sttHeaders['Authorization'] = 'Bearer ' + process.env.LITELLM_API_KEY;
       var base = process.env.LITELLM_API_BASE.replace(/\/+$/, '');