From 2df51f7aa33a0d6d5e3f0967a22c4160234c922b Mon Sep 17 00:00:00 2001
From: PRABHU KIRAN VANDRANKI <72809214+VANDRANKI@users.noreply.github.com>
Date: Tue, 5 May 2026 14:34:59 -0400
Subject: [PATCH] fix(vertex): include system in request_data for partner model
 token counting

---
 litellm/llms/vertex_ai/vertex_ai_partner_models/main.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/litellm/llms/vertex_ai/vertex_ai_partner_models/main.py b/litellm/llms/vertex_ai/vertex_ai_partner_models/main.py
index 123d925f7c1..361ae24d430 100644
--- a/litellm/llms/vertex_ai/vertex_ai_partner_models/main.py
+++ b/litellm/llms/vertex_ai/vertex_ai_partner_models/main.py
@@ -277,6 +277,7 @@ class VertexAIPartnerModels(VertexBase):
         vertex_project=None,
         vertex_location=None,
         vertex_credentials=None,
+        system=None,
     ):
         """
         Count tokens for Vertex AI partner models (Anthropic Claude, Mistral, etc.)
@@ -318,6 +319,8 @@ class VertexAIPartnerModels(VertexBase):
                 "model": model,
                 "messages": messages,
             }
+            if system is not None:
+                request_data["system"] = system
 
             # Prepare litellm_params with credentials
             _litellm_params = litellm_params.copy()