diff --git a/src/api/models/bedrock.py b/src/api/models/bedrock.py
index 96cdc05..6063ffb 100644
--- a/src/api/models/bedrock.py
+++ b/src/api/models/bedrock.py
@@ -463,6 +463,7 @@ class BedrockModel(BaseChatModel):
                 message = ChatResponseMessage(
                     tool_calls=[
                         ToolCall(
+                            index=0,
                             type="function",
                             id=delta["toolUse"]["toolUseId"],
                             function=ResponseFunction(
@@ -484,7 +485,7 @@ class BedrockModel(BaseChatModel):
                 message = ChatResponseMessage(
                     tool_calls=[
                         ToolCall(
-                            type="function",
+                            index=0,
                             function=ResponseFunction(
                                 arguments=delta["toolUse"]["input"],
                             )
diff --git a/src/api/schema.py b/src/api/schema.py
index 2b2f2fb..0ceb88b 100644
--- a/src/api/schema.py
+++ b/src/api/schema.py
@@ -22,6 +22,7 @@ class ResponseFunction(BaseModel):
 
 
 class ToolCall(BaseModel):
+    index: int | None = None
     id: str | None = None
     type: Literal["function"] = "function"
     function: ResponseFunction