[dx] Improve Agent file upload DX

examples/agent_with_file_upload.py

@@ -0,0 +1,43 @@
+# To run the example:
+# poetry install
+# poetry run python examples/agent_with_file_upload.py
+
+from glean.api_client import Glean, models
+import os
+
+
+def main():
+    with Glean(
+        api_token=os.getenv("GLEAN_API_TOKEN", ""),
+        domain=os.getenv("GLEAN_DOMAIN", "customerName"),
+    ) as glean:
+
+        # 1. Upload the file first
+        file_content = b"name,role\nAlice,Engineer\nBob,Manager"
+
+        upload_result = glean.client.chat.upload_files(
+            files=[
+                models.File(
+                    file_name="employees.csv",
+                    content=file_content
+                )
+            ]
+        )
+
+        # 2. Get the ID (string) from the response
+        file_id = upload_result.files[0].id
+
+        # 3. Run the agent passing the file ID (NOT the file object)
+        res = glean.client.agents.run(
+            agent_id=os.getenv("GLEAN_AGENT_ID", "<agent-id>"),
+            input={
+                # Pass the file ID string to the input parameter
+                "file": file_id,
+                "query": "Who is the manager?"
+            }
+        )
+
+        print(res)
+
+if __name__ == "__main__":
+    main()

src/glean/api_client/_hooks/agent_file_upload_error_hook.py

@@ -0,0 +1,81 @@
+"""Custom hook to provide helpful error messages for agent file upload issues."""
+
+from typing import Optional, Tuple, Union
+import httpx
+from glean.api_client._hooks.types import AfterErrorContext, AfterErrorHook
+
+
+class AgentFileUploadErrorHook(AfterErrorHook):
+    """
+    Hook that detects when users incorrectly pass file objects to agents.run()
+    and provides clear guidance on the correct two-step upload workflow.
+
+    This hook intercepts 400 errors from agent run operations that contain
+    "permission" in the error message, which typically indicates a file was
+    passed incorrectly instead of a file ID.
+    """
+
+    def after_error(
+        self,
+        hook_ctx: AfterErrorContext,
+        response: Optional[httpx.Response],
+        error: Optional[Exception],
+    ) -> Union[Tuple[Optional[httpx.Response], Optional[Exception]], Exception]:
+        """
+        Intercept agent run errors and enhance them with helpful file upload guidance.
+
+        Args:
+            hook_ctx: Context about the operation being performed
+            response: The HTTP response (if available)
+            error: The exception that was raised
+
+        Returns:
+            Either a tuple of (response, error) to continue normal error handling,
+            or a new Exception to replace the original error.
+        """
+        # Only intercept 400 errors from agent run operations
+        if (
+            response is not None
+            and response.status_code == 400
+            and hook_ctx.operation_id in ["createAndWaitRun", "createAndStreamRun"]
+        ):
+            error_message = str(error) if error else ""
+
+            # Check if this looks like a file upload error
+            # (API returns "permission" error when file objects are passed incorrectly)
+            if "permission" in error_message.lower():
+                # Create enhanced error message with clear instructions
+                enhanced_message = (
+                    "Agent file upload error: When using agents with file inputs, "
+                    "you must follow a two-step process:\n"
+                    "\n"
+                    "1. First, upload files using client.chat.upload_files():\n"
+                    "   from glean.api_client import models\n"
+                    "   \n"
+                    "   # Upload the file\n"
+                    "   upload_result = client.chat.upload_files(\n"
+                    "       files=[\n"
+                    "           models.File(\n"
+                    "               file_name='data.csv',\n"
+                    "               content=file_content  # bytes or file-like object\n"
+                    "           )\n"
+                    "       ]\n"
+                    "   )\n"
+                    "\n"
+                    "2. Then, pass the returned file IDs (not file objects) in the input field:\n"
+                    "   result = client.agents.run(\n"
+                    "       agent_id='<agent-id>',\n"
+                    "       input={\n"
+                    "           'my_file': upload_result.files[0].id  # Use the file ID string\n"
+                    "       }\n"
+                    "   )\n"
+                    "\n"
+                    "For a complete example, see: examples/agent_with_file_upload.py\n"
+                    f"\nOriginal error: {error_message}"
+                )
+
+                # Return new exception with enhanced message
+                return Exception(enhanced_message)
+
+        # Pass through all other errors unchanged
+        return response, error

src/glean/api_client/_hooks/registration.py

@@ -1,5 +1,6 @@
 from .types import Hooks
 from .multipart_fix_hook import MultipartFileFieldFixHook
+from .agent_file_upload_error_hook import AgentFileUploadErrorHook
 
 
 # This file is only ever generated once on the first generation and then is free to be modified.
@@ -15,3 +16,6 @@ def init_hooks(hooks: Hooks):
 
     # Register hook to fix multipart file field names that incorrectly have '[]' suffix
     hooks.register_sdk_init_hook(MultipartFileFieldFixHook())
+
+    # Register hook to provide helpful error messages for agent file upload issues
+    hooks.register_after_error_hook(AgentFileUploadErrorHook())