diff --git a/libs/core/langchain_core/messages/v1.py b/libs/core/langchain_core/messages/v1.py
index e68db4b6a47..66063813846 100644
--- a/libs/core/langchain_core/messages/v1.py
+++ b/libs/core/langchain_core/messages/v1.py
@@ -7,7 +7,7 @@ Each message has content that may be comprised of content blocks, defined under
 import json
 import uuid
 from dataclasses import dataclass, field
-from typing import Any, Literal, Optional, Union, cast, get_args
+from typing import Any, Literal, Optional, TypeGuard, Union, cast, get_args
 
 from pydantic import BaseModel
 from typing_extensions import TypedDict
@@ -29,6 +29,23 @@ from langchain_core.utils._merge import merge_dicts, merge_lists
 from langchain_core.utils.json import parse_partial_json
 
 
+def is_tool_call_block(block: types.ContentBlock) -> TypeGuard[types.ToolCall]:
+    """Type guard to check if a content block is a tool call."""
+    return block.get("type") == "tool_call"
+
+
+def is_text_block(block: types.ContentBlock) -> TypeGuard[types.TextContentBlock]:
+    """Type guard to check if a content block is a text block."""
+    return block.get("type") == "text"
+
+
+def is_invalid_tool_call_block(
+    block: types.ContentBlock,
+) -> TypeGuard[types.InvalidToolCall]:
+    """Type guard to check if a content block is an invalid tool call."""
+    return block.get("type") == "invalid_tool_call"
+
+
 def _ensure_id(id_val: Optional[str]) -> str:
     """Ensure the ID is a valid string, generating a new UUID if not provided.
 
@@ -177,20 +194,17 @@ class AIMessage:
                 if "id" in tool_call and tool_call["id"] in content_tool_calls:
                     continue
                 self.content.append(tool_call)
-        self._tool_calls: list[types.ToolCall] = cast(
-            "list[types.ToolCall]",
-            [block for block in self.content if block.get("type") == "tool_call"],
-        )
+        self._tool_calls: list[types.ToolCall] = [
+            block for block in self.content if is_tool_call_block(block)
+        ]
         self.invalid_tool_calls = invalid_tool_calls or []
 
     @property
     def text(self) -> Optional[str]:
         """Extract all text content from the AI message as a string."""
-        text_blocks = [block for block in self.content if block.get("type") == "text"]
+        text_blocks = [block for block in self.content if is_text_block(block)]
         if text_blocks:
-            return "".join(
-                cast("types.TextContentBlock", block)["text"] for block in text_blocks
-            )
+            return "".join(block["text"] for block in text_blocks)
         return None
 
     @property
@@ -198,11 +212,9 @@ class AIMessage:
         """Get the tool calls made by the AI."""
         if self._tool_calls:
             return self._tool_calls
-        tool_calls = [
-            block for block in self.content if block.get("type") == "tool_call"
-        ]
+        tool_calls = [block for block in self.content if is_tool_call_block(block)]
         if tool_calls:
-            self._tool_calls = cast("list[types.ToolCall]", tool_calls)
+            self._tool_calls = tool_calls
         return self._tool_calls
 
     @tool_calls.setter
@@ -356,11 +368,9 @@ class AIMessageChunk(AIMessage):
     @property
     def text(self) -> Optional[str]:
         """Extract all text content from the AI message as a string."""
-        text_blocks = [block for block in self.content if block.get("type") == "text"]
+        text_blocks = [block for block in self.content if is_text_block(block)]
         if text_blocks:
-            return "".join(
-                cast("types.TextContentBlock", block)["text"] for block in text_blocks
-            )
+            return "".join(block["text"] for block in text_blocks)
         return None
 
     @property
@@ -383,11 +393,9 @@ class AIMessageChunk(AIMessage):
         """Get the tool calls made by the AI."""
         if self._tool_calls:
             return self._tool_calls
-        tool_calls = [
-            block for block in self.content if block.get("type") == "tool_call"
-        ]
+        tool_calls = [block for block in self.content if is_tool_call_block(block)]
         if tool_calls:
-            self._tool_calls = cast("list[types.ToolCall]", tool_calls)
+            self._tool_calls = tool_calls
         return self._tool_calls
 
     @tool_calls.setter