diff --git a/litellm/llms/anthropic.py b/litellm/llms/anthropic.py
index d533fdbb2..9f1346b0c 100644
--- a/litellm/llms/anthropic.py
+++ b/litellm/llms/anthropic.py
@@ -1122,6 +1122,7 @@ class ModelResponseIterator:
         self.streaming_response = streaming_response
         self.response_iterator = self.streaming_response
         self.content_blocks: List[ContentBlockDelta] = []
+        self.tool_index = -1
 
     def check_empty_tool_call_args(self) -> bool:
         """
@@ -1171,7 +1172,7 @@ class ModelResponseIterator:
                             "name": None,
                             "arguments": content_block["delta"]["partial_json"],
                         },
-                        "index": content_block["index"],
+                        "index": self.tool_index,
                     }
             elif type_chunk == "content_block_start":
                 """
@@ -1183,6 +1184,7 @@ class ModelResponseIterator:
                 if content_block_start["content_block"]["type"] == "text":
                     text = content_block_start["content_block"]["text"]
                 elif content_block_start["content_block"]["type"] == "tool_use":
+                    self.tool_index += 1
                     tool_use = {
                         "id": content_block_start["content_block"]["id"],
                         "type": "function",
@@ -1190,7 +1192,7 @@ class ModelResponseIterator:
                             "name": content_block_start["content_block"]["name"],
                             "arguments": "",
                         },
-                        "index": content_block_start["index"],
+                        "index": self.tool_index,
                     }
             elif type_chunk == "content_block_stop":
                 content_block_stop = ContentBlockStop(**chunk)  # type: ignore
@@ -1204,7 +1206,7 @@ class ModelResponseIterator:
                             "name": None,
                             "arguments": "{}",
                         },
-                        "index": content_block_stop["index"],
+                        "index": self.tool_index,
                     }
             elif type_chunk == "message_delta":
                 """
diff --git a/litellm/tests/test_anthropic_completion.py b/litellm/tests/test_anthropic_completion.py
index b3c4745c9..b5e01d448 100644
--- a/litellm/tests/test_anthropic_completion.py
+++ b/litellm/tests/test_anthropic_completion.py
@@ -10,6 +10,7 @@ from dotenv import load_dotenv
 
 import litellm.types
 import litellm.types.utils
+from litellm.llms.anthropic import ModelResponseIterator
 
 load_dotenv()
 import io
@@ -150,6 +151,74 @@ def test_anthropic_completion_e2e(stream):
         assert message_stop_received is True
 
 
+anthropic_chunk_list = [
+    {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "To"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " answer"}},
+    {"type": "content_block_delta", "index": 0,
+     "delta": {"type": "text_delta", "text": " your question about the weather"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " in Boston and Los"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " Angeles today, I'll"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " need to"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " use"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " the"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " get_current_weather"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " function"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " for"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " both"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " cities"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": ". Let"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " me fetch"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " that"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " information"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " for"}},
+    {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": " you."}},
+    {"type": "content_block_stop", "index": 0},
+    {"type": "content_block_start", "index": 1,
+     "content_block": {"type": "tool_use", "id": "toolu_12345", "name": "get_current_weather", "input": {}}},
+    {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": ""}},
+    {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": "{\"locat"}},
+    {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": "ion\": \"Bos"}},
+    {"type": "content_block_delta", "index": 1, "delta": {"type": "input_json_delta", "partial_json": "ton, MA\"}"}},
+    {"type": "content_block_stop", "index": 1},
+    {"type": "content_block_start", "index": 2,
+     "content_block": {"type": "tool_use", "id": "toolu_023423423", "name": "get_current_weather", "input": {}}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": ""}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "{\"l"}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "oca"}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "tio"}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "n\": \"Lo"}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "s Angel"}},
+    {"type": "content_block_delta", "index": 2, "delta": {"type": "input_json_delta", "partial_json": "es, CA\"}"}},
+    {"type": "content_block_stop", "index": 2},
+    {"type": "message_delta", "delta": {"stop_reason": "tool_use", "stop_sequence": None},
+     "usage": {"output_tokens": 137}},
+    {"type": "message_stop"}
+]
+
+
+def test_anthropic_tool_streaming():
+    """
+    OpenAI starts tool_use indexes at 0 for the first tool, regardless of preceding text.
+
+    Anthropic gives tool_use indexes starting at the first chunk, meaning they often start at 1
+    when they should start at 0
+    """
+    litellm.set_verbose = True
+    response_iter = ModelResponseIterator([], False)
+
+    # First index is 0, we'll start earlier because incrementing is easier
+    correct_tool_index = -1
+    for chunk in anthropic_chunk_list:
+        parsed_chunk = response_iter.chunk_parser(chunk)
+        if tool_use := parsed_chunk.get('tool_use'):
+
+            # We only increment when a new block starts
+            if tool_use.get('id') is not None:
+                correct_tool_index += 1
+            assert tool_use['index'] == correct_tool_index
+
+
 @pytest.mark.asyncio
 async def test_anthropic_router_completion_e2e():
     litellm.set_verbose = True
@@ -275,4 +344,4 @@ def test_anthropic_tool_calling_translation():
     print(translated_params["messages"])
 
     assert len(translated_params["messages"]) > 0
-    assert translated_params["messages"][0]["role"] == "user"
+    assert translated_params["messages"][0]["role"] == "user"
\ No newline at end of file