diff --git a/libs/core/langchain_core/messages/v1.py b/libs/core/langchain_core/messages/v1.py
index f4537265370..e68db4b6a47 100644
--- a/libs/core/langchain_core/messages/v1.py
+++ b/libs/core/langchain_core/messages/v1.py
@@ -177,9 +177,10 @@ class AIMessage:
                 if "id" in tool_call and tool_call["id"] in content_tool_calls:
                     continue
                 self.content.append(tool_call)
-        self._tool_calls = [
-            block for block in self.content if block.get("type") == "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.invalid_tool_calls = invalid_tool_calls or []
 
     @property
@@ -187,7 +188,9 @@ class AIMessage:
         """Extract all text content from the AI message as a string."""
         text_blocks = [block for block in self.content if block.get("type") == "text"]
         if text_blocks:
-            return "".join(block["text"] for block in text_blocks)
+            return "".join(
+                cast("types.TextContentBlock", block)["text"] for block in text_blocks
+            )
         return None
 
     @property
@@ -195,10 +198,12 @@ 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["type"] == "tool_call"]
+        tool_calls = [
+            block for block in self.content if block.get("type") == "tool_call"
+        ]
         if tool_calls:
-            self._tool_calls = tool_calls
-        return [block for block in self.content if block["type"] == "tool_call"]
+            self._tool_calls = cast("list[types.ToolCall]", tool_calls)
+        return self._tool_calls
 
     @tool_calls.setter
     def tool_calls(self, value: list[types.ToolCall]) -> None:
@@ -351,9 +356,11 @@ 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["type"] == "text"]
+        text_blocks = [block for block in self.content if block.get("type") == "text"]
         if text_blocks:
-            return "".join(block["text"] for block in text_blocks)
+            return "".join(
+                cast("types.TextContentBlock", block)["text"] for block in text_blocks
+            )
         return None
 
     @property
@@ -365,7 +372,10 @@ class AIMessageChunk(AIMessage):
             if block.get("type") == "reasoning" and "reasoning" in block
         ]
         if text_blocks:
-            return "".join(block["reasoning"] for block in text_blocks)
+            return "".join(
+                cast("types.ReasoningContentBlock", block).get("reasoning", "")
+                for block in text_blocks
+            )
         return None
 
     @property
@@ -377,7 +387,7 @@ class AIMessageChunk(AIMessage):
             block for block in self.content if block.get("type") == "tool_call"
         ]
         if tool_calls:
-            self._tool_calls = tool_calls
+            self._tool_calls = cast("list[types.ToolCall]", tool_calls)
         return self._tool_calls
 
     @tool_calls.setter
@@ -561,7 +571,9 @@ class HumanMessage:
             Concatenated string of all text blocks in the message.
         """
         return "".join(
-            block["text"] for block in self.content if block.get("type") == "text"
+            cast("types.TextContentBlock", block)["text"]
+            for block in self.content
+            if block.get("type") == "text"
         )
 
 
@@ -640,7 +652,9 @@ class SystemMessage:
     def text(self) -> str:
         """Extract all text content from the system message."""
         return "".join(
-            block["text"] for block in self.content if block.get("type") == "text"
+            cast("types.TextContentBlock", block)["text"]
+            for block in self.content
+            if block.get("type") == "text"
         )
 
 
@@ -732,7 +746,9 @@ class ToolMessage:
     def text(self) -> str:
         """Extract all text content from the tool message."""
         return "".join(
-            block["text"] for block in self.content if block.get("type") == "text"
+            cast("types.TextContentBlock", block)["text"]
+            for block in self.content
+            if block.get("type") == "text"
         )
 
     def __post_init__(self) -> None: