diff --git a/src/providers/google-vertex-ai/chatComplete.ts b/src/providers/google-vertex-ai/chatComplete.ts
index f20440d2..b2d8fc64 100644
--- a/src/providers/google-vertex-ai/chatComplete.ts
+++ b/src/providers/google-vertex-ai/chatComplete.ts
@@ -91,10 +91,10 @@ export const VertexGoogleChatCompleteConfig: ProviderConfig = {
                 functionCall: {
                   name: tool_call.function.name,
                   args: JSON.parse(tool_call.function.arguments),
-                  ...(tool_call.function.thought_signature && {
-                    thought_signature: tool_call.function.thought_signature,
-                  }),
                 },
+                ...(tool_call.function.thought_signature && {
+                  thoughtSignature: tool_call.function.thought_signature,
+                }),
               });
             });
           } else if (message.role === 'tool') {
diff --git a/src/providers/google/chatComplete.ts b/src/providers/google/chatComplete.ts
index 1ac3f7d5..239d363b 100644
--- a/src/providers/google/chatComplete.ts
+++ b/src/providers/google/chatComplete.ts
@@ -219,10 +219,10 @@ export const GoogleChatCompleteConfig: ProviderConfig = {
                 functionCall: {
                   name: tool_call.function.name,
                   args: JSON.parse(tool_call.function.arguments),
-                  ...(tool_call.function.thought_signature && {
-                    thought_signature: tool_call.function.thought_signature,
-                  }),
                 },
+                ...(tool_call.function.thought_signature && {
+                  thoughtSignature: tool_call.function.thought_signature,
+                }),
               });
             });
           } else if (message.role === 'tool') {