diff --git a/libs/partners/anthropic/langchain_anthropic/chat_models.py b/libs/partners/anthropic/langchain_anthropic/chat_models.py
index 43904445a74..57b8e01792b 100644
--- a/libs/partners/anthropic/langchain_anthropic/chat_models.py
+++ b/libs/partners/anthropic/langchain_anthropic/chat_models.py
@@ -166,6 +166,7 @@ _ANTHROPIC_EXTRA_FIELDS: set[str] = {
     "allowed_callers",
     "cache_control",
     "defer_loading",
+    "eager_input_streaming",
     "input_examples",
 }
 """Valid Anthropic-specific extra fields"""
diff --git a/libs/partners/anthropic/tests/unit_tests/test_chat_models.py b/libs/partners/anthropic/tests/unit_tests/test_chat_models.py
index 1fa7a4b5cf6..02862bdef74 100644
--- a/libs/partners/anthropic/tests/unit_tests/test_chat_models.py
+++ b/libs/partners/anthropic/tests/unit_tests/test_chat_models.py
@@ -16,7 +16,7 @@ from blockbuster import blockbuster_ctx
 from langchain_core.exceptions import ContextOverflowError
 from langchain_core.messages import AIMessage, HumanMessage, SystemMessage, ToolMessage
 from langchain_core.runnables import RunnableBinding
-from langchain_core.tools import BaseTool
+from langchain_core.tools import BaseTool, tool
 from langchain_core.tracers.base import BaseTracer
 from langchain_core.tracers.schemas import Run
 from pydantic import BaseModel, Field, SecretStr, ValidationError
@@ -2007,9 +2007,9 @@ def test_tool_search_with_deferred_tools() -> None:
 
     # Find the calculator tool in the payload
     calculator_tool = None
-    for tool in payload["tools"]:
-        if isinstance(tool, dict) and tool.get("name") == "calculator":
-            calculator_tool = tool
+    for tool_ in payload["tools"]:
+        if isinstance(tool_, dict) and tool_.get("name") == "calculator":
+            calculator_tool = tool_
             break
 
     assert calculator_tool is not None
@@ -2264,7 +2264,6 @@ def test_output_config_without_effort() -> None:
 
 def test_extras_with_defer_loading() -> None:
     """Test that extras with `defer_loading` are merged into tool definitions."""
-    from langchain_core.tools import tool
 
     @tool(extras={"defer_loading": True})
     def get_weather(location: str) -> str:
@@ -2293,7 +2292,6 @@ def test_extras_with_defer_loading() -> None:
 
 def test_extras_with_cache_control() -> None:
     """Test that extras with `cache_control` are merged into tool definitions."""
-    from langchain_core.tools import tool
 
     @tool(extras={"cache_control": {"type": "ephemeral"}})
     def search_files(query: str) -> str:
@@ -2318,9 +2316,31 @@ def test_extras_with_cache_control() -> None:
     assert search_tool.get("cache_control") == {"type": "ephemeral"}
 
 
+def test_extras_with_fine_grained_streaming() -> None:
+    @tool(extras={"eager_input_streaming": True})
+    def tell_story(story: str) -> None:
+        """Tell a story."""
+
+    model = ChatAnthropic(model=MODEL_NAME)  # type: ignore[call-arg]
+    model_with_tools = model.bind_tools([tell_story])
+
+    payload = model_with_tools._get_request_payload(  # type: ignore[attr-defined]
+        "test",
+        **model_with_tools.kwargs,  # type: ignore[attr-defined]
+    )
+
+    tell_story_tool = None
+    for tool_def in payload["tools"]:
+        if isinstance(tool_def, dict) and tool_def.get("name") == "tell_story":
+            tell_story_tool = tool_def
+            break
+
+    assert tell_story_tool is not None
+    assert tell_story_tool.get("eager_input_streaming") is True
+
+
 def test_extras_with_input_examples() -> None:
     """Test that extras with `input_examples` are merged into tool definitions."""
-    from langchain_core.tools import tool
 
     @tool(
         extras={
@@ -2363,7 +2383,6 @@ def test_extras_with_input_examples() -> None:
 
 def test_extras_with_multiple_fields() -> None:
     """Test that multiple extra fields can be specified together."""
-    from langchain_core.tools import tool
 
     @tool(
         extras={