Implementation:Openai Openai python Response Output Item Type

Knowledge Sources	Openai_Openai_python OpenAI API Reference
Domains	API_Types, Responses_API
Last Updated	2026-02-15 00:00 GMT

Overview

Discriminated union type alias and supporting models for representing all possible response output items provided by the openai-python SDK.

Description

ResponseOutputItem is a TypeAlias representing a discriminated union of all possible output item types that can appear in the output array of a Responses API response. It is discriminated on the type field using PropertyInfo(discriminator="type"). Unlike ResponseItem (which includes both input and output items), ResponseOutputItem is scoped to output-only items: output messages, tool calls, reasoning items, compaction items, image generation calls, local shell calls, MCP-related items, and custom tool calls.

The module also defines several supporting Pydantic models:

• ImageGenerationCall - An image generation request with id, result, status, and type fields.
• LocalShellCallAction - Describes a shell command to execute with command, env, timeout, user, and working directory.
• LocalShellCall - A tool call to run a command on the local shell.
• McpCall - An invocation of a tool on an MCP server.
• McpListToolsTool - A tool available on an MCP server.
• McpListTools - A list of tools available on an MCP server.
• McpApprovalRequest - A request for human approval of a tool invocation.

Usage

Import ResponseOutputItem when you need a type annotation covering all possible output items from a response. Import individual supporting classes when working with specific output item types.

Code Reference

Source Location

• Repository: openai-python
• File: src/openai/types/responses/response_output_item.py

Signature

ResponseOutputItem: TypeAlias = Annotated[
    Union[
        ResponseOutputMessage,
        ResponseFileSearchToolCall,
        ResponseFunctionToolCall,
        ResponseFunctionWebSearch,
        ResponseComputerToolCall,
        ResponseReasoningItem,
        ResponseCompactionItem,
        ImageGenerationCall,
        ResponseCodeInterpreterToolCall,
        LocalShellCall,
        ResponseFunctionShellToolCall,
        ResponseFunctionShellToolCallOutput,
        ResponseApplyPatchToolCall,
        ResponseApplyPatchToolCallOutput,
        McpCall,
        McpListTools,
        McpApprovalRequest,
        ResponseCustomToolCall,
    ],
    PropertyInfo(discriminator="type"),
]

Import

from openai.types.responses import ResponseOutputItem

I/O Contract

Union Members

Type	Discriminator Value	Description
ResponseOutputMessage	"message"	An output message from the model.
ResponseFileSearchToolCall	"file_search_call"	A file search tool call.
ResponseFunctionToolCall	"function_call"	A function tool call.
ResponseFunctionWebSearch	"web_search_call"	A web search tool call.
ResponseComputerToolCall	"computer_call"	A computer use tool call.
ResponseReasoningItem	"reasoning"	A reasoning item from the model.
ResponseCompactionItem	"compaction"	A compaction item.
ImageGenerationCall	"image_generation_call"	An image generation request.
ResponseCodeInterpreterToolCall	"code_interpreter_call"	A code interpreter tool call.
LocalShellCall	"local_shell_call"	A local shell command call.
ResponseFunctionShellToolCall	"function_shell_call"	A function shell tool call.
ResponseFunctionShellToolCallOutput	"function_shell_call_output"	Output from a function shell tool call.
ResponseApplyPatchToolCall	"apply_patch_call"	An apply patch tool call.
ResponseApplyPatchToolCallOutput	"apply_patch_call_output"	Output from an apply patch tool call.
McpCall	"mcp_call"	An MCP tool call invocation.
McpListTools	"mcp_list_tools"	A list of tools from an MCP server.
McpApprovalRequest	"mcp_approval_request"	An MCP approval request.
ResponseCustomToolCall	"custom_tool_call"	A custom tool call.

Usage Examples

import openai

client = openai.OpenAI()

response = client.responses.create(
    model="gpt-4o",
    input="Explain quantum computing briefly.",
)

for item in response.output:
    # item is typed as ResponseOutputItem (discriminated union)
    if item.type == "message":
        for content in item.content:
            if content.type == "output_text":
                print(content.text)
    elif item.type == "reasoning":
        print(f"Reasoning item: {item.id}")
    elif item.type == "function_call":
        print(f"Function call: {item.name}({item.arguments})")
    elif item.type == "mcp_call":
        print(f"MCP call: {item.name} on {item.server_label}")

Related Pages

• Environment:Openai_Openai_python_Python_3_9_Plus