diff --git a/_client.py b/_client.py
index 4db2526..b1fbe68 100644
--- a/_client.py
+++ b/_client.py
@@ -2,6 +2,8 @@
 
 from daytona import Daytona, DaytonaConfig, DaytonaNotFoundError, Sandbox
 
+MAX_FILE_SIZE = 100 * 1024 * 1024  # 100 MB
+
 
 def build_client(credentials: dict[str, Any]) -> Daytona:
     config = DaytonaConfig(api_key=credentials["api_key"])
diff --git a/tools/download_file.py b/tools/download_file.py
index 76429b1..685fafd 100644
--- a/tools/download_file.py
+++ b/tools/download_file.py
@@ -6,7 +6,7 @@
 from dify_plugin import Tool
 from dify_plugin.entities.tool import ToolInvokeMessage
 
-from _client import build_client, get_sandbox
+from _client import MAX_FILE_SIZE, build_client, get_sandbox
 
 
 class DownloadFileTool(Tool):
@@ -21,11 +21,25 @@ def _invoke(self, tool_parameters: dict[str, Any]) -> Generator[ToolInvokeMessag
 
         daytona = build_client(self.runtime.credentials)
         sandbox = get_sandbox(daytona, sandbox_id)
+
+        info = sandbox.fs.get_file_info(remote_path)
+        if info.size and info.size > MAX_FILE_SIZE:
+            raise ValueError(
+                f"File size ({info.size} bytes) exceeds maximum allowed size "
+                f"({MAX_FILE_SIZE} bytes)."
+            )
+
         content = sandbox.fs.download_file(remote_path)
 
         if content is None:
             raise ValueError(f"Could not read '{remote_path}' from sandbox '{sandbox_id}': no content returned")
 
+        if len(content) > MAX_FILE_SIZE:
+            raise ValueError(
+                f"Downloaded file size ({len(content)} bytes) exceeds maximum allowed size "
+                f"({MAX_FILE_SIZE} bytes)."
+            )
+
         filename = os.path.basename(remote_path) or "downloaded_file"
         mime_type, _ = mimetypes.guess_type(filename)
         if not mime_type:
diff --git a/tools/upload_file.py b/tools/upload_file.py
index f4120c2..e81638d 100644
--- a/tools/upload_file.py
+++ b/tools/upload_file.py
@@ -5,7 +5,7 @@
 from dify_plugin.entities.tool import ToolInvokeMessage
 from dify_plugin.file.file import File
 
-from _client import build_client, get_sandbox
+from _client import MAX_FILE_SIZE, build_client, get_sandbox
 
 
 class UploadFileTool(Tool):
@@ -24,9 +24,16 @@ def _invoke(self, tool_parameters: dict[str, Any]) -> Generator[ToolInvokeMessag
         if not isinstance(file, File):
             raise ValueError(f"Expected file parameter to be a File, got {type(file).__name__}")
 
+        blob = file.blob
+        if len(blob) > MAX_FILE_SIZE:
+            raise ValueError(
+                f"File size ({len(blob)} bytes) exceeds maximum allowed size "
+                f"({MAX_FILE_SIZE} bytes)."
+            )
+
         daytona = build_client(self.runtime.credentials)
         sandbox = get_sandbox(daytona, sandbox_id)
-        sandbox.fs.upload_file(file.blob, remote_path)
+        sandbox.fs.upload_file(blob, remote_path)
 
         yield self.create_json_message({
             "success": True,