Uploading a CSV file for use with the code interpreter tool fails

[Soremwar]

Please read this first

• Have you read the docs? Yes, they don't mention whether this is possible or not
• Have you searched for related issues? Yes

Describe the bug

Returning a ToolOutputFileContent from a tool fails with the error openai.BadRequestError: Error code: 400 - {'error': {'message': 'The file type you uploaded is not supported. Please try again with a PDF', 'type': 'invalid_request_error', 'param': 'input', 'code': 'unsupported_file'}}. This was attempted with a CSV file, which should be supported according to https://platform.openai.com/docs/guides/tools-code-interpreter#supported-files

Granted, this seems to apply to directly interfacing with code interpreter in the API, but my tool is CodeInterpreter enabled in the following way

AGENT = Agent(
	name="My agent",
	model="gpt-5.1",
	tools=[
		CodeInterpreterTool({
			"type": "code_interpreter",
			"container": {
				"type": "auto",
			},
		}),
	],
)

Debug information

• Agents SDK version: 0.7.0
• Python version: 3.12.9

Repro steps

from agents import Agent, CodeInterpreterTool, function_tool, ToolOutputFileContent
import base64

@function_tool
def get_data() -> str | ToolOutputFileContent:
	parsed_data = "COL_1,COL_2\n1,2\n3,4"
	encoded_data = "data:text/csv;base64," + base64.b64encode(parsed_data.encode("utf-8")).decode("utf-8")
	return ToolOutputFileContent(file_data=encoded_data, filename="data.csv")

AGENT = Agent(
	name="My agent",
	model="gpt-5.1",
	tools=[
		get_data,
		CodeInterpreterTool({
			"type": "code_interpreter",
			"container": {
				"type": "auto",
			},
		}),
	],
)

Expected behavior

The agent should orchestrate passing the files to the code interpreter

[seratch]

This could be confusing, but the input item attachments do not support various types of files (currently, only image and pdf). For your need, you need to call files.upload API first, and then attach the file ID this way:

from openai import OpenAI

client = OpenAI()

file_upload = client.files.create(file=("test.csv", "...".encode("utf-8")), purpose="assistants")

response = client.responses.create(
    model="gpt-4.1",
    instructions="...",
    input="Do the calculation on the uploaded file.",
    tools=[
        {
            "type": "code_interpreter",
            "container": {"type": "auto", "file_ids": [file_upload.id]},
        },
    ],
)

[github-actions]

This issue is stale because it has been open for 7 days with no activity.