API Reference

Chat

Completions

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Create chat completion

client.Chat.Completions.New(ctx, body) (*ChatCompletion, error)

POST/chat/completions

Starting a new project? We recommend trying Responses to take advantage of the latest OpenAI platform features. Compare Chat Completions with Responses.

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Creates a model response for the given chat conversation. Learn more in the text generation, vision, and audio guides.

Parameter support can differ depending on the model used to generate the response, particularly for newer reasoning models. Parameters that are only supported for reasoning models are noted below. For the current state of unsupported parameters in reasoning models, refer to the reasoning guide.

ParametersExpand Collapse

body ChatCompletionNewParams

Messages param.Field[[]ChatCompletionMessageParamUnionResp]

A list of messages comprising the conversation so far. Depending on the model you use, different message types (modalities) are supported, like text, images, and audio.

type ChatCompletionDeveloperMessageParamResp struct{…}

Developer-provided instructions that the model should follow, regardless of messages sent by the user. With o1 models and newer, developer messages replace the previous system messages.

Content ChatCompletionDeveloperMessageParamContentUnionResp

The contents of the developer message.

Accepts one of the following:

string

[]ChatCompletionContentPartText

Text string

The text content.

Type Text

The type of the content part.

Role Developer

The role of the messages author, in this case developer.

Name stringoptional

An optional name for the participant. Provides the model information to differentiate between participants of the same role.

type ChatCompletionSystemMessageParamResp struct{…}

Developer-provided instructions that the model should follow, regardless of messages sent by the user. With o1 models and newer, use developer messages for this purpose instead.

Content ChatCompletionSystemMessageParamContentUnionResp

The contents of the system message.

Accepts one of the following:

string

[]ChatCompletionContentPartText

Text string

The text content.

Type Text

The type of the content part.

Role System

The role of the messages author, in this case system.

Name stringoptional

An optional name for the participant. Provides the model information to differentiate between participants of the same role.

type ChatCompletionUserMessageParamResp struct{…}

Messages sent by an end user, containing prompts or additional context information.

Content ChatCompletionUserMessageParamContentUnionResp

The contents of the user message.

Accepts one of the following:

string

[]ChatCompletionContentPartUnion

Accepts one of the following:

type ChatCompletionContentPartText struct{…}

Learn about text inputs.

Text string

The text content.

Type Text

The type of the content part.

type ChatCompletionContentPartImage struct{…}

Learn about image inputs.

ImageURL ChatCompletionContentPartImageImageURL

URL string

Either a URL of the image or the base64 encoded image data.

formaturi

Detail stringoptional

Specifies the detail level of the image. Learn more in the Vision guide.

Accepts one of the following:

const ChatCompletionContentPartImageImageURLDetailAuto ChatCompletionContentPartImageImageURLDetail = "auto"

const ChatCompletionContentPartImageImageURLDetailLow ChatCompletionContentPartImageImageURLDetail = "low"

const ChatCompletionContentPartImageImageURLDetailHigh ChatCompletionContentPartImageImageURLDetail = "high"

Type ImageURL

The type of the content part.

type ChatCompletionContentPartInputAudio struct{…}

Learn about audio inputs.

InputAudio ChatCompletionContentPartInputAudioInputAudio

Data string

Base64 encoded audio data.

Format string

The format of the encoded audio data. Currently supports "wav" and "mp3".

Accepts one of the following:

const ChatCompletionContentPartInputAudioInputAudioFormatWAV ChatCompletionContentPartInputAudioInputAudioFormat = "wav"

const ChatCompletionContentPartInputAudioInputAudioFormatMP3 ChatCompletionContentPartInputAudioInputAudioFormat = "mp3"

Type InputAudio

The type of the content part. Always input_audio.

ChatCompletionContentPartFile

File ChatCompletionContentPartFileFile

FileData stringoptional

The base64 encoded file data, used when passing the file to the model as a string.

FileID stringoptional

The ID of an uploaded file to use as input.

Filename stringoptional

The name of the file, used when passing the file to the model as a string.

Type File

The type of the content part. Always file.

Role User

The role of the messages author, in this case user.

Name stringoptional

An optional name for the participant. Provides the model information to differentiate between participants of the same role.

type ChatCompletionAssistantMessageParamResp struct{…}

Messages sent by the model in response to user messages.

Role Assistant

The role of the messages author, in this case assistant.

Audio ChatCompletionAssistantMessageParamAudioRespoptional

Data about a previous audio response from the model. Learn more.

ID string

Unique identifier for a previous audio response from the model.

Content ChatCompletionAssistantMessageParamContentUnionRespoptional

The contents of the assistant message. Required unless tool_calls or function_call is specified.

Accepts one of the following:

string

[]ChatCompletionAssistantMessageParamContentArrayOfContentPartUnionResp

Accepts one of the following:

type ChatCompletionContentPartText struct{…}

Learn about text inputs.

Text string

The text content.

Type Text

The type of the content part.

type ChatCompletionContentPartRefusal struct{…}

Refusal string

The refusal message generated by the model.

Type Refusal

The type of the content part.

DeprecatedFunctionCall ChatCompletionAssistantMessageParamFunctionCallRespoptional

Deprecated and replaced by tool_calls. The name and arguments of a function that should be called, as generated by the model.

Arguments string

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name string

The name of the function to call.

Name stringoptional

An optional name for the participant. Provides the model information to differentiate between participants of the same role.

Refusal stringoptional

The refusal message by the assistant.

ToolCalls []ChatCompletionMessageToolCallUnionoptional

The tool calls generated by the model, such as function calls.

Accepts one of the following:

type ChatCompletionMessageFunctionToolCall struct{…}

A call to a function tool created by the model.

ID string

The ID of the tool call.

Function ChatCompletionMessageFunctionToolCallFunction

The function that the model called.

Arguments string

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name string

The name of the function to call.

Type Function

The type of the tool. Currently, only function is supported.

type ChatCompletionMessageCustomToolCall struct{…}

A call to a custom tool created by the model.

ID string

The ID of the tool call.

Custom ChatCompletionMessageCustomToolCallCustom

The custom tool that the model called.

Input string

The input for the custom tool call generated by the model.

Name string

The name of the custom tool to call.

Type Custom

The type of the tool. Always custom.

type ChatCompletionToolMessageParamResp struct{…}

Content ChatCompletionToolMessageParamContentUnionResp

The contents of the tool message.

Accepts one of the following:

string

[]ChatCompletionContentPartText

Text string

The text content.

Type Text

The type of the content part.

Role Tool

The role of the messages author, in this case tool.

ToolCallID string

Tool call that this message is responding to.

type ChatCompletionFunctionMessageParamResp struct{…}

Content string

The contents of the function message.

Name string

The name of the function to call.

Role Function

The role of the messages author, in this case function.

Model param.Field[ChatModel]

Model ID used to generate the response, like gpt-4o or o3. OpenAI offers a wide range of models with different capabilities, performance characteristics, and price points. Refer to the model guide to browse and compare available models.

string

type ChatModel string

Accepts one of the following:

const ChatModelGPT5_2 ChatModel = "gpt-5.2"

const ChatModelGPT5_2_2025_12_11 ChatModel = "gpt-5.2-2025-12-11"

const ChatModelGPT5_2ChatLatest ChatModel = "gpt-5.2-chat-latest"

const ChatModelGPT5_2Pro ChatModel = "gpt-5.2-pro"

const ChatModelGPT5_2Pro2025_12_11 ChatModel = "gpt-5.2-pro-2025-12-11"

const ChatModelGPT5_1 ChatModel = "gpt-5.1"

const ChatModelGPT5_1_2025_11_13 ChatModel = "gpt-5.1-2025-11-13"

const ChatModelGPT5_1Codex ChatModel = "gpt-5.1-codex"

const ChatModelGPT5_1Mini ChatModel = "gpt-5.1-mini"

const ChatModelGPT5_1ChatLatest ChatModel = "gpt-5.1-chat-latest"

const ChatModelGPT5 ChatModel = "gpt-5"

const ChatModelGPT5Mini ChatModel = "gpt-5-mini"

const ChatModelGPT5Nano ChatModel = "gpt-5-nano"

const ChatModelGPT5_2025_08_07 ChatModel = "gpt-5-2025-08-07"

const ChatModelGPT5Mini2025_08_07 ChatModel = "gpt-5-mini-2025-08-07"

const ChatModelGPT5Nano2025_08_07 ChatModel = "gpt-5-nano-2025-08-07"

const ChatModelGPT5ChatLatest ChatModel = "gpt-5-chat-latest"

const ChatModelGPT4_1 ChatModel = "gpt-4.1"

const ChatModelGPT4_1Mini ChatModel = "gpt-4.1-mini"

const ChatModelGPT4_1Nano ChatModel = "gpt-4.1-nano"

const ChatModelGPT4_1_2025_04_14 ChatModel = "gpt-4.1-2025-04-14"

const ChatModelGPT4_1Mini2025_04_14 ChatModel = "gpt-4.1-mini-2025-04-14"

const ChatModelGPT4_1Nano2025_04_14 ChatModel = "gpt-4.1-nano-2025-04-14"

const ChatModelO4Mini ChatModel = "o4-mini"

const ChatModelO4Mini2025_04_16 ChatModel = "o4-mini-2025-04-16"

const ChatModelO3 ChatModel = "o3"

const ChatModelO3_2025_04_16 ChatModel = "o3-2025-04-16"

const ChatModelO3Mini ChatModel = "o3-mini"

const ChatModelO3Mini2025_01_31 ChatModel = "o3-mini-2025-01-31"

const ChatModelO1 ChatModel = "o1"

const ChatModelO1_2024_12_17 ChatModel = "o1-2024-12-17"

const ChatModelO1Preview ChatModel = "o1-preview"

const ChatModelO1Preview2024_09_12 ChatModel = "o1-preview-2024-09-12"

const ChatModelO1Mini ChatModel = "o1-mini"

const ChatModelO1Mini2024_09_12 ChatModel = "o1-mini-2024-09-12"

const ChatModelGPT4o ChatModel = "gpt-4o"

const ChatModelGPT4o2024_11_20 ChatModel = "gpt-4o-2024-11-20"

const ChatModelGPT4o2024_08_06 ChatModel = "gpt-4o-2024-08-06"

const ChatModelGPT4o2024_05_13 ChatModel = "gpt-4o-2024-05-13"

const ChatModelGPT4oAudioPreview ChatModel = "gpt-4o-audio-preview"

const ChatModelGPT4oAudioPreview2024_10_01 ChatModel = "gpt-4o-audio-preview-2024-10-01"

const ChatModelGPT4oAudioPreview2024_12_17 ChatModel = "gpt-4o-audio-preview-2024-12-17"

const ChatModelGPT4oAudioPreview2025_06_03 ChatModel = "gpt-4o-audio-preview-2025-06-03"

const ChatModelGPT4oMiniAudioPreview ChatModel = "gpt-4o-mini-audio-preview"

const ChatModelGPT4oMiniAudioPreview2024_12_17 ChatModel = "gpt-4o-mini-audio-preview-2024-12-17"

const ChatModelGPT4oSearchPreview ChatModel = "gpt-4o-search-preview"

const ChatModelGPT4oMiniSearchPreview ChatModel = "gpt-4o-mini-search-preview"

const ChatModelGPT4oSearchPreview2025_03_11 ChatModel = "gpt-4o-search-preview-2025-03-11"

const ChatModelGPT4oMiniSearchPreview2025_03_11 ChatModel = "gpt-4o-mini-search-preview-2025-03-11"

const ChatModelChatgpt4oLatest ChatModel = "chatgpt-4o-latest"

const ChatModelCodexMiniLatest ChatModel = "codex-mini-latest"

const ChatModelGPT4oMini ChatModel = "gpt-4o-mini"

const ChatModelGPT4oMini2024_07_18 ChatModel = "gpt-4o-mini-2024-07-18"

const ChatModelGPT4Turbo ChatModel = "gpt-4-turbo"

const ChatModelGPT4Turbo2024_04_09 ChatModel = "gpt-4-turbo-2024-04-09"

const ChatModelGPT4_0125Preview ChatModel = "gpt-4-0125-preview"

const ChatModelGPT4TurboPreview ChatModel = "gpt-4-turbo-preview"

const ChatModelGPT4_1106Preview ChatModel = "gpt-4-1106-preview"

const ChatModelGPT4VisionPreview ChatModel = "gpt-4-vision-preview"

const ChatModelGPT4 ChatModel = "gpt-4"

const ChatModelGPT4_0314 ChatModel = "gpt-4-0314"

const ChatModelGPT4_0613 ChatModel = "gpt-4-0613"

const ChatModelGPT4_32k ChatModel = "gpt-4-32k"

const ChatModelGPT4_32k0314 ChatModel = "gpt-4-32k-0314"

const ChatModelGPT4_32k0613 ChatModel = "gpt-4-32k-0613"

const ChatModelGPT3_5Turbo ChatModel = "gpt-3.5-turbo"

const ChatModelGPT3_5Turbo16k ChatModel = "gpt-3.5-turbo-16k"

const ChatModelGPT3_5Turbo0301 ChatModel = "gpt-3.5-turbo-0301"

const ChatModelGPT3_5Turbo0613 ChatModel = "gpt-3.5-turbo-0613"

const ChatModelGPT3_5Turbo1106 ChatModel = "gpt-3.5-turbo-1106"

const ChatModelGPT3_5Turbo0125 ChatModel = "gpt-3.5-turbo-0125"

const ChatModelGPT3_5Turbo16k0613 ChatModel = "gpt-3.5-turbo-16k-0613"

Audio param.Field[ChatCompletionAudioParamResp]optional

Parameters for audio output. Required when audio output is requested with modalities: ["audio"]. Learn more.

FrequencyPenalty param.Field[float64]optional

Number between -2.0 and 2.0. Positive values penalize new tokens based on their existing frequency in the text so far, decreasing the model's likelihood to repeat the same line verbatim.

minimum-2

maximum2

DeprecatedFunctionCall param.Field[ChatCompletionNewParamsFunctionCallUnion]optional

Deprecated in favor of tool_choice.

Controls which (if any) function is called by the model.

none means the model will not call a function and instead generates a message.

auto means the model can pick between generating a message or calling a function.

Specifying a particular function via {"name": "my_function"} forces the model to call that function.

none is the default when no functions are present. auto is the default if functions are present.

string

Accepts one of the following:

const ChatCompletionNewParamsFunctionCallFunctionCallModeNone ChatCompletionNewParamsFunctionCallFunctionCallMode = "none"

const ChatCompletionNewParamsFunctionCallFunctionCallModeAuto ChatCompletionNewParamsFunctionCallFunctionCallMode = "auto"

type ChatCompletionFunctionCallOption struct{…}

Specifying a particular function via {"name": "my_function"} forces the model to call that function.

Name string

The name of the function to call.

DeprecatedFunctions param.Field[[]ChatCompletionNewParamsFunction]optional

Deprecated in favor of tools.

A list of functions the model may generate JSON inputs for.

Name string

The name of the function to be called. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

Description stringoptional

A description of what the function does, used by the model to choose when and how to call the function.

Parameters FunctionParametersoptional

The parameters the functions accepts, described as a JSON Schema object. See the guide for examples, and the JSON Schema reference for documentation about the format.

Omitting parameters defines a function with an empty parameter list.

LogitBias param.Field[map[string, int64]]optional

Modify the likelihood of specified tokens appearing in the completion.

Accepts a JSON object that maps tokens (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically, the bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model, but values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should result in a ban or exclusive selection of the relevant token.

Logprobs param.Field[bool]optional

Whether to return log probabilities of the output tokens or not. If true, returns the log probabilities of each output token returned in the content of message.

MaxCompletionTokens param.Field[int64]optional

An upper bound for the number of tokens that can be generated for a completion, including visible output tokens and reasoning tokens.

DeprecatedMaxTokens param.Field[int64]optional

The maximum number of tokens that can be generated in the chat completion. This value can be used to control costs for text generated via API.

This value is now deprecated in favor of max_completion_tokens, and is not compatible with o-series models.

Metadata param.Field[Metadata]optional

Set of 16 key-value pairs that can be attached to an object. This can be useful for storing additional information about the object in a structured format, and querying for objects via API or the dashboard.

Keys are strings with a maximum length of 64 characters. Values are strings with a maximum length of 512 characters.

Modalities param.Field[[]string]optional

Output types that you would like the model to generate. Most models are capable of generating text, which is the default:

["text"]

The gpt-4o-audio-preview model can also be used to generate audio. To request that this model generate both text and audio responses, you can use:

["text", "audio"]

const ChatCompletionNewParamsModalityText ChatCompletionNewParamsModality = "text"

const ChatCompletionNewParamsModalityAudio ChatCompletionNewParamsModality = "audio"

N param.Field[int64]optional

How many chat completion choices to generate for each input message. Note that you will be charged based on the number of generated tokens across all of the choices. Keep n as 1 to minimize costs.

minimum1

maximum128

ParallelToolCalls param.Field[bool]optional

Whether to enable parallel function calling during tool use.

Prediction param.Field[ChatCompletionPredictionContent]optional

Static predicted output content, such as the content of a text file that is being regenerated.

PresencePenalty param.Field[float64]optional

Number between -2.0 and 2.0. Positive values penalize new tokens based on whether they appear in the text so far, increasing the model's likelihood to talk about new topics.

minimum-2

maximum2

PromptCacheKey param.Field[string]optional

Used by OpenAI to cache responses for similar requests to optimize your cache hit rates. Replaces the user field. Learn more.

PromptCacheRetention param.Field[ChatCompletionNewParamsPromptCacheRetention]optional

The retention policy for the prompt cache. Set to 24h to enable extended prompt caching, which keeps cached prefixes active for longer, up to a maximum of 24 hours. Learn more.

const ChatCompletionNewParamsPromptCacheRetentionInMemory ChatCompletionNewParamsPromptCacheRetention = "in-memory"

const ChatCompletionNewParamsPromptCacheRetention24h ChatCompletionNewParamsPromptCacheRetention = "24h"

ReasoningEffort param.Field[ReasoningEffort]optional

Constrains effort on reasoning for reasoning models. Currently supported values are none, minimal, low, medium, high, and xhigh. Reducing reasoning effort can result in faster responses and fewer tokens used on reasoning in a response.

• gpt-5.1 defaults to none, which does not perform reasoning. The supported reasoning values for gpt-5.1 are none, low, medium, and high. Tool calls are supported for all reasoning values in gpt-5.1.
• All models before gpt-5.1 default to medium reasoning effort, and do not support none.
• The gpt-5-pro model defaults to (and only supports) high reasoning effort.
• xhigh is supported for all models after gpt-5.1-codex-max.

ResponseFormat param.Field[ChatCompletionNewParamsResponseFormatUnion]optional

An object specifying the format that the model must output.

Setting to { "type": "json_schema", "json_schema": {...} } enables Structured Outputs which ensures the model will match your supplied JSON schema. Learn more in the Structured Outputs guide.

Setting to { "type": "json_object" } enables the older JSON mode, which ensures the message the model generates is valid JSON. Using json_schema is preferred for models that support it.

type ResponseFormatText struct{…}

Default response format. Used to generate text responses.

Type Text

The type of response format being defined. Always text.

type ResponseFormatJSONSchema struct{…}

JSON Schema response format. Used to generate structured JSON responses. Learn more about Structured Outputs.

JSONSchema ResponseFormatJSONSchemaJSONSchema

Structured Outputs configuration options, including a JSON Schema.

Name string

The name of the response format. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

Description stringoptional

A description of what the response format is for, used by the model to determine how to respond in the format.

Schema map[string, any]optional

The schema for the response format, described as a JSON Schema object. Learn how to build JSON schemas here.

Strict booloptional

Whether to enable strict schema adherence when generating the output. If set to true, the model will always follow the exact schema defined in the schema field. Only a subset of JSON Schema is supported when strict is true. To learn more, read the Structured Outputs guide.

Type JSONSchema

The type of response format being defined. Always json_schema.

type ResponseFormatJSONObject struct{…}

JSON object response format. An older method of generating JSON responses. Using json_schema is recommended for models that support it. Note that the model will not generate JSON without a system or user message instructing it to do so.

Type JSONObject

The type of response format being defined. Always json_object.

SafetyIdentifier param.Field[string]optional

A stable identifier used to help detect users of your application that may be violating OpenAI's usage policies. The IDs should be a string that uniquely identifies each user. We recommend hashing their username or email address, in order to avoid sending us any identifying information. Learn more.

DeprecatedSeed param.Field[int64]optional

This feature is in Beta. If specified, our system will make a best effort to sample deterministically, such that repeated requests with the same seed and parameters should return the same result. Determinism is not guaranteed, and you should refer to the system_fingerprint response parameter to monitor changes in the backend.

minimum-9223372036854776000

maximum9223372036854776000

ServiceTier param.Field[ChatCompletionNewParamsServiceTier]optional

Specifies the processing type used for serving the request.

• If set to 'auto', then the request will be processed with the service tier configured in the Project settings. Unless otherwise configured, the Project will use 'default'.
• If set to 'default', then the request will be processed with the standard pricing and performance for the selected model.
• If set to 'flex' or 'priority', then the request will be processed with the corresponding service tier.
• When not set, the default behavior is 'auto'.

When the service_tier parameter is set, the response body will include the service_tier value based on the processing mode actually used to serve the request. This response value may be different from the value set in the parameter.

const ChatCompletionNewParamsServiceTierAuto ChatCompletionNewParamsServiceTier = "auto"

const ChatCompletionNewParamsServiceTierDefault ChatCompletionNewParamsServiceTier = "default"

const ChatCompletionNewParamsServiceTierFlex ChatCompletionNewParamsServiceTier = "flex"

const ChatCompletionNewParamsServiceTierScale ChatCompletionNewParamsServiceTier = "scale"

const ChatCompletionNewParamsServiceTierPriority ChatCompletionNewParamsServiceTier = "priority"

Stop param.Field[ChatCompletionNewParamsStopUnion]optional

Not supported with latest reasoning models o3 and o4-mini.

Up to 4 sequences where the API will stop generating further tokens. The returned text will not contain the stop sequence.

string

[]string

Store param.Field[bool]optional

Whether or not to store the output of this chat completion request for use in our model distillation or evals products.

Supports text and image inputs. Note: image inputs over 8MB will be dropped.

StreamOptions param.Field[ChatCompletionStreamOptions]optional

Options for streaming response. Only set this when you set stream: true.

Temperature param.Field[float64]optional

What sampling temperature to use, between 0 and 2. Higher values like 0.8 will make the output more random, while lower values like 0.2 will make it more focused and deterministic. We generally recommend altering this or top_p but not both.

minimum0

maximum2

ToolChoice param.Field[ChatCompletionToolChoiceOptionUnion]optional

Controls which (if any) tool is called by the model. none means the model will not call any tool and instead generates a message. auto means the model can pick between generating a message or calling one or more tools. required means the model must call one or more tools. Specifying a particular tool via {"type": "function", "function": {"name": "my_function"}} forces the model to call that tool.

none is the default when no tools are present. auto is the default if tools are present.

Tools param.Field[[]ChatCompletionToolUnion]optional

A list of tools the model may call. You can provide either custom tools or function tools.

type ChatCompletionFunctionTool struct{…}

A function tool that can be used to generate a response.

Function FunctionDefinition

Name string

The name of the function to be called. Must be a-z, A-Z, 0-9, or contain underscores and dashes, with a maximum length of 64.

Description stringoptional

A description of what the function does, used by the model to choose when and how to call the function.

Parameters FunctionParametersoptional

The parameters the functions accepts, described as a JSON Schema object. See the guide for examples, and the JSON Schema reference for documentation about the format.

Omitting parameters defines a function with an empty parameter list.

Strict booloptional

Whether to enable strict schema adherence when generating the function call. If set to true, the model will follow the exact schema defined in the parameters field. Only a subset of JSON Schema is supported when strict is true. Learn more about Structured Outputs in the function calling guide.

Type Function

The type of the tool. Currently, only function is supported.

type ChatCompletionCustomTool struct{…}

A custom tool that processes input using a specified format.

Custom ChatCompletionCustomToolCustom

Properties of the custom tool.

Name string

The name of the custom tool, used to identify it in tool calls.

Description stringoptional

Optional description of the custom tool, used to provide more context.

Format ChatCompletionCustomToolCustomFormatUnionoptional

The input format for the custom tool. Default is unconstrained text.

Accepts one of the following:

ChatCompletionCustomToolCustomFormatText

Type Text

Unconstrained text format. Always text.

ChatCompletionCustomToolCustomFormatGrammar

Grammar ChatCompletionCustomToolCustomFormatGrammarGrammar

Your chosen grammar.

Definition string

The grammar definition.

Syntax string

The syntax of the grammar definition. One of lark or regex.

Accepts one of the following:

const ChatCompletionCustomToolCustomFormatGrammarGrammarSyntaxLark ChatCompletionCustomToolCustomFormatGrammarGrammarSyntax = "lark"

const ChatCompletionCustomToolCustomFormatGrammarGrammarSyntaxRegex ChatCompletionCustomToolCustomFormatGrammarGrammarSyntax = "regex"

Type Grammar

Grammar format. Always grammar.

Type Custom

The type of the custom tool. Always custom.

TopLogprobs param.Field[int64]optional

An integer between 0 and 20 specifying the number of most likely tokens to return at each token position, each with an associated log probability. logprobs must be set to true if this parameter is used.

minimum0

maximum20

TopP param.Field[float64]optional

An alternative to sampling with temperature, called nucleus sampling, where the model considers the results of the tokens with top_p probability mass. So 0.1 means only the tokens comprising the top 10% probability mass are considered.

We generally recommend altering this or temperature but not both.

minimum0

maximum1

DeprecatedUser param.Field[string]optional

This field is being replaced by safety_identifier and prompt_cache_key. Use prompt_cache_key instead to maintain caching optimizations. A stable identifier for your end-users. Used to boost cache hit rates by better bucketing similar requests and to help OpenAI detect and prevent abuse. Learn more.

Verbosity param.Field[ChatCompletionNewParamsVerbosity]optional

Constrains the verbosity of the model's response. Lower values will result in more concise responses, while higher values will result in more verbose responses. Currently supported values are low, medium, and high.

const ChatCompletionNewParamsVerbosityLow ChatCompletionNewParamsVerbosity = "low"

const ChatCompletionNewParamsVerbosityMedium ChatCompletionNewParamsVerbosity = "medium"

const ChatCompletionNewParamsVerbosityHigh ChatCompletionNewParamsVerbosity = "high"

WebSearchOptions param.Field[ChatCompletionNewParamsWebSearchOptions]optional

This tool searches the web for relevant results to use in a response. Learn more about the web search tool.

SearchContextSize stringoptional

High level guidance for the amount of context window space to use for the search. One of low, medium, or high. medium is the default.

Accepts one of the following:

const ChatCompletionNewParamsWebSearchOptionsSearchContextSizeLow ChatCompletionNewParamsWebSearchOptionsSearchContextSize = "low"

const ChatCompletionNewParamsWebSearchOptionsSearchContextSizeMedium ChatCompletionNewParamsWebSearchOptionsSearchContextSize = "medium"

const ChatCompletionNewParamsWebSearchOptionsSearchContextSizeHigh ChatCompletionNewParamsWebSearchOptionsSearchContextSize = "high"

UserLocation ChatCompletionNewParamsWebSearchOptionsUserLocationoptional

Approximate location parameters for the search.

Approximate ChatCompletionNewParamsWebSearchOptionsUserLocationApproximate

Approximate location parameters for the search.

City stringoptional

Free text input for the city of the user, e.g. San Francisco.

Country stringoptional

The two-letter ISO country code of the user, e.g. US.

Region stringoptional

Free text input for the region of the user, e.g. California.

Timezone stringoptional

The IANA timezone of the user, e.g. America/Los_Angeles.

Type Approximate

The type of location approximation. Always approximate.

ReturnsExpand Collapse

type ChatCompletion struct{…}

Represents a chat completion response returned by model, based on the provided input.

ID string

A unique identifier for the chat completion.

Choices []ChatCompletionChoice

A list of chat completion choices. Can be more than one if n is greater than 1.

FinishReason string

The reason the model stopped generating tokens. This will be stop if the model hit a natural stop point or a provided stop sequence, length if the maximum number of tokens specified in the request was reached, content_filter if content was omitted due to a flag from our content filters, tool_calls if the model called a tool, or function_call (deprecated) if the model called a function.

Accepts one of the following:

const ChatCompletionChoiceFinishReasonStop ChatCompletionChoiceFinishReason = "stop"

const ChatCompletionChoiceFinishReasonLength ChatCompletionChoiceFinishReason = "length"

const ChatCompletionChoiceFinishReasonToolCalls ChatCompletionChoiceFinishReason = "tool_calls"

const ChatCompletionChoiceFinishReasonContentFilter ChatCompletionChoiceFinishReason = "content_filter"

const ChatCompletionChoiceFinishReasonFunctionCall ChatCompletionChoiceFinishReason = "function_call"

Index int64

The index of the choice in the list of choices.

Logprobs ChatCompletionChoiceLogprobs

Log probability information for the choice.

Content []ChatCompletionTokenLogprob

A list of message content tokens with log probability information.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

TopLogprobs []ChatCompletionTokenLogprobTopLogprob

List of the most likely tokens and their log probability, at this token position. In rare cases, there may be fewer than the number of requested top_logprobs returned.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

Refusal []ChatCompletionTokenLogprob

A list of message refusal tokens with log probability information.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

TopLogprobs []ChatCompletionTokenLogprobTopLogprob

List of the most likely tokens and their log probability, at this token position. In rare cases, there may be fewer than the number of requested top_logprobs returned.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

Message ChatCompletionMessage

A chat completion message generated by the model.

Content string

The contents of the message.

Refusal string

The refusal message generated by the model.

Role Assistant

The role of the author of this message.

Annotations []ChatCompletionMessageAnnotationoptional

Annotations for the message, when applicable, as when using the web search tool.

Type URLCitation

The type of the URL citation. Always url_citation.

URLCitation ChatCompletionMessageAnnotationURLCitation

A URL citation when using web search.

EndIndex int64

The index of the last character of the URL citation in the message.

StartIndex int64

The index of the first character of the URL citation in the message.

Title string

The title of the web resource.

URL string

The URL of the web resource.

Audio ChatCompletionAudiooptional

If the audio output modality is requested, this object contains data about the audio response from the model. Learn more.

ID string

Unique identifier for this audio response.

Data string

Base64 encoded audio bytes generated by the model, in the format specified in the request.

ExpiresAt int64

The Unix timestamp (in seconds) for when this audio response will no longer be accessible on the server for use in multi-turn conversations.

Transcript string

Transcript of the audio generated by the model.

DeprecatedFunctionCall ChatCompletionMessageFunctionCalloptional

Deprecated and replaced by tool_calls. The name and arguments of a function that should be called, as generated by the model.

Arguments string

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name string

The name of the function to call.

ToolCalls []ChatCompletionMessageToolCallUnionoptional

The tool calls generated by the model, such as function calls.

Accepts one of the following:

type ChatCompletionMessageFunctionToolCall struct{…}

A call to a function tool created by the model.

ID string

The ID of the tool call.

Function ChatCompletionMessageFunctionToolCallFunction

The function that the model called.

Arguments string

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name string

The name of the function to call.

Type Function

The type of the tool. Currently, only function is supported.

type ChatCompletionMessageCustomToolCall struct{…}

A call to a custom tool created by the model.

ID string

The ID of the tool call.

Custom ChatCompletionMessageCustomToolCallCustom

The custom tool that the model called.

Input string

The input for the custom tool call generated by the model.

Name string

The name of the custom tool to call.

Type Custom

The type of the tool. Always custom.

Created int64

The Unix timestamp (in seconds) of when the chat completion was created.

Model string

The model used for the chat completion.

Object ChatCompletion

The object type, which is always chat.completion.

ServiceTier ChatCompletionServiceTieroptional

Specifies the processing type used for serving the request.

• If set to 'auto', then the request will be processed with the service tier configured in the Project settings. Unless otherwise configured, the Project will use 'default'.
• If set to 'default', then the request will be processed with the standard pricing and performance for the selected model.
• If set to 'flex' or 'priority', then the request will be processed with the corresponding service tier.
• When not set, the default behavior is 'auto'.

When the service_tier parameter is set, the response body will include the service_tier value based on the processing mode actually used to serve the request. This response value may be different from the value set in the parameter.

Accepts one of the following:

const ChatCompletionServiceTierAuto ChatCompletionServiceTier = "auto"

const ChatCompletionServiceTierDefault ChatCompletionServiceTier = "default"

const ChatCompletionServiceTierFlex ChatCompletionServiceTier = "flex"

const ChatCompletionServiceTierScale ChatCompletionServiceTier = "scale"

const ChatCompletionServiceTierPriority ChatCompletionServiceTier = "priority"

DeprecatedSystemFingerprint stringoptional

This fingerprint represents the backend configuration that the model runs with.

Can be used in conjunction with the seed request parameter to understand when backend changes have been made that might impact determinism.

Usage CompletionUsageoptional

Usage statistics for the completion request.

CompletionTokens int64

Number of tokens in the generated completion.

PromptTokens int64

Number of tokens in the prompt.

TotalTokens int64

Total number of tokens used in the request (prompt + completion).

CompletionTokensDetails CompletionUsageCompletionTokensDetailsoptional

Breakdown of tokens used in a completion.

AcceptedPredictionTokens int64optional

When using Predicted Outputs, the number of tokens in the prediction that appeared in the completion.

AudioTokens int64optional

Audio input tokens generated by the model.

ReasoningTokens int64optional

Tokens generated by the model for reasoning.

RejectedPredictionTokens int64optional

When using Predicted Outputs, the number of tokens in the prediction that did not appear in the completion. However, like reasoning tokens, these tokens are still counted in the total completion tokens for purposes of billing, output, and context window limits.

PromptTokensDetails CompletionUsagePromptTokensDetailsoptional

Breakdown of tokens used in the prompt.

AudioTokens int64optional

Audio input tokens present in the prompt.

CachedTokens int64optional

Cached tokens present in the prompt.

type ChatCompletionChunk struct{…}

Represents a streamed chunk of a chat completion response returned by the model, based on the provided input. Learn more.

ID string

A unique identifier for the chat completion. Each chunk has the same ID.

Choices []ChatCompletionChunkChoice

A list of chat completion choices. Can contain more than one elements if n is greater than 1. Can also be empty for the last chunk if you set stream_options: {"include_usage": true}.

Delta ChatCompletionChunkChoiceDelta

A chat completion delta generated by streamed model responses.

Content stringoptional

The contents of the chunk message.

DeprecatedFunctionCall ChatCompletionChunkChoiceDeltaFunctionCalloptional

Deprecated and replaced by tool_calls. The name and arguments of a function that should be called, as generated by the model.

Arguments stringoptional

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name stringoptional

The name of the function to call.

Refusal stringoptional

The refusal message generated by the model.

Role stringoptional

The role of the author of this message.

Accepts one of the following:

const ChatCompletionChunkChoiceDeltaRoleDeveloper ChatCompletionChunkChoiceDeltaRole = "developer"

const ChatCompletionChunkChoiceDeltaRoleSystem ChatCompletionChunkChoiceDeltaRole = "system"

const ChatCompletionChunkChoiceDeltaRoleUser ChatCompletionChunkChoiceDeltaRole = "user"

const ChatCompletionChunkChoiceDeltaRoleAssistant ChatCompletionChunkChoiceDeltaRole = "assistant"

const ChatCompletionChunkChoiceDeltaRoleTool ChatCompletionChunkChoiceDeltaRole = "tool"

ToolCalls []ChatCompletionChunkChoiceDeltaToolCalloptional

Index int64

ID stringoptional

The ID of the tool call.

Function ChatCompletionChunkChoiceDeltaToolCallFunctionoptional

Arguments stringoptional

The arguments to call the function with, as generated by the model in JSON format. Note that the model does not always generate valid JSON, and may hallucinate parameters not defined by your function schema. Validate the arguments in your code before calling your function.

Name stringoptional

The name of the function to call.

Type stringoptional

The type of the tool. Currently, only function is supported.

FinishReason string

The reason the model stopped generating tokens. This will be stop if the model hit a natural stop point or a provided stop sequence, length if the maximum number of tokens specified in the request was reached, content_filter if content was omitted due to a flag from our content filters, tool_calls if the model called a tool, or function_call (deprecated) if the model called a function.

Accepts one of the following:

const ChatCompletionChunkChoiceFinishReasonStop ChatCompletionChunkChoiceFinishReason = "stop"

const ChatCompletionChunkChoiceFinishReasonLength ChatCompletionChunkChoiceFinishReason = "length"

const ChatCompletionChunkChoiceFinishReasonToolCalls ChatCompletionChunkChoiceFinishReason = "tool_calls"

const ChatCompletionChunkChoiceFinishReasonContentFilter ChatCompletionChunkChoiceFinishReason = "content_filter"

const ChatCompletionChunkChoiceFinishReasonFunctionCall ChatCompletionChunkChoiceFinishReason = "function_call"

Index int64

The index of the choice in the list of choices.

Logprobs ChatCompletionChunkChoiceLogprobsoptional

Log probability information for the choice.

Content []ChatCompletionTokenLogprob

A list of message content tokens with log probability information.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

TopLogprobs []ChatCompletionTokenLogprobTopLogprob

List of the most likely tokens and their log probability, at this token position. In rare cases, there may be fewer than the number of requested top_logprobs returned.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

Refusal []ChatCompletionTokenLogprob

A list of message refusal tokens with log probability information.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

TopLogprobs []ChatCompletionTokenLogprobTopLogprob

List of the most likely tokens and their log probability, at this token position. In rare cases, there may be fewer than the number of requested top_logprobs returned.

Token string

The token.

Bytes []int64

A list of integers representing the UTF-8 bytes representation of the token. Useful in instances where characters are represented by multiple tokens and their byte representations must be combined to generate the correct text representation. Can be null if there is no bytes representation for the token.

Logprob float64

The log probability of this token, if it is within the top 20 most likely tokens. Otherwise, the value -9999.0 is used to signify that the token is very unlikely.

Created int64

The Unix timestamp (in seconds) of when the chat completion was created. Each chunk has the same timestamp.

Model string

The model to generate the completion.

Object ChatCompletionChunk

The object type, which is always chat.completion.chunk.

ServiceTier ChatCompletionChunkServiceTieroptional

Specifies the processing type used for serving the request.

• If set to 'auto', then the request will be processed with the service tier configured in the Project settings. Unless otherwise configured, the Project will use 'default'.
• If set to 'default', then the request will be processed with the standard pricing and performance for the selected model.
• If set to 'flex' or 'priority', then the request will be processed with the corresponding service tier.
• When not set, the default behavior is 'auto'.

When the service_tier parameter is set, the response body will include the service_tier value based on the processing mode actually used to serve the request. This response value may be different from the value set in the parameter.

Accepts one of the following:

const ChatCompletionChunkServiceTierAuto ChatCompletionChunkServiceTier = "auto"

const ChatCompletionChunkServiceTierDefault ChatCompletionChunkServiceTier = "default"

const ChatCompletionChunkServiceTierFlex ChatCompletionChunkServiceTier = "flex"

const ChatCompletionChunkServiceTierScale ChatCompletionChunkServiceTier = "scale"

const ChatCompletionChunkServiceTierPriority ChatCompletionChunkServiceTier = "priority"

DeprecatedSystemFingerprint stringoptional

This fingerprint represents the backend configuration that the model runs with. Can be used in conjunction with the seed request parameter to understand when backend changes have been made that might impact determinism.

Usage CompletionUsageoptional

An optional field that will only be present when you set stream_options: {"include_usage": true} in your request. When present, it contains a null value except for the last chunk which contains the token usage statistics for the entire request.

NOTE: If the stream is interrupted or cancelled, you may not receive the final usage chunk which contains the total token usage for the request.

CompletionTokens int64

Number of tokens in the generated completion.

PromptTokens int64

Number of tokens in the prompt.

TotalTokens int64

Total number of tokens used in the request (prompt + completion).

CompletionTokensDetails CompletionUsageCompletionTokensDetailsoptional

Breakdown of tokens used in a completion.

AcceptedPredictionTokens int64optional

When using Predicted Outputs, the number of tokens in the prediction that appeared in the completion.

AudioTokens int64optional

Audio input tokens generated by the model.

ReasoningTokens int64optional

Tokens generated by the model for reasoning.

RejectedPredictionTokens int64optional

When using Predicted Outputs, the number of tokens in the prediction that did not appear in the completion. However, like reasoning tokens, these tokens are still counted in the total completion tokens for purposes of billing, output, and context window limits.

PromptTokensDetails CompletionUsagePromptTokensDetailsoptional

Breakdown of tokens used in the prompt.

AudioTokens int64optional

Audio input tokens present in the prompt.

CachedTokens int64optional

Cached tokens present in the prompt.

Create chat completion

Go

HTTP

TypeScript

Python

Java

Go

Ruby

package main

import (
  "context"
  "fmt"

  "github.com/openai/openai-go"
  "github.com/openai/openai-go/option"
  "github.com/openai/openai-go/shared"
)

func main() {
  client := openai.NewClient(
    option.WithAPIKey("My API Key"),
  )
  chatCompletion, err := client.Chat.Completions.New(context.TODO(), openai.ChatCompletionNewParams{
    Messages: []openai.ChatCompletionMessageParamUnion{openai.ChatCompletionMessageParamUnion{
      OfDeveloper: &openai.ChatCompletionDeveloperMessageParam{
        Content: openai.ChatCompletionDeveloperMessageParamContentUnion{
          OfString: openai.String("string"),
        },
      },
    }},
    Model: shared.ChatModelGPT4o,
  })
  if err != nil {
    panic(err.Error())
  }
  fmt.Printf("%+v\n", chatCompletion)
}

200 example

{
  "id": "id",
  "choices": [
    {
      "finish_reason": "stop",
      "index": 0,
      "logprobs": {
        "content": [
          {
            "token": "token",
            "bytes": [
              0
            ],
            "logprob": 0,
            "top_logprobs": [
              {
                "token": "token",
                "bytes": [
                  0
                ],
                "logprob": 0
              }
            ]
          }
        ],
        "refusal": [
          {
            "token": "token",
            "bytes": [
              0
            ],
            "logprob": 0,
            "top_logprobs": [
              {
                "token": "token",
                "bytes": [
                  0
                ],
                "logprob": 0
              }
            ]
          }
        ]
      },
      "message": {
        "content": "content",
        "refusal": "refusal",
        "role": "assistant",
        "annotations": [
          {
            "type": "url_citation",
            "url_citation": {
              "end_index": 0,
              "start_index": 0,
              "title": "title",
              "url": "url"
            }
          }
        ],
        "audio": {
          "id": "id",
          "data": "data",
          "expires_at": 0,
          "transcript": "transcript"
        },
        "function_call": {
          "arguments": "arguments",
          "name": "name"
        },
        "tool_calls": [
          {
            "id": "id",
            "function": {
              "arguments": "arguments",
              "name": "name"
            },
            "type": "function"
          }
        ]
      }
    }
  ],
  "created": 0,
  "model": "model",
  "object": "chat.completion",
  "service_tier": "auto",
  "system_fingerprint": "system_fingerprint",
  "usage": {
    "completion_tokens": 0,
    "prompt_tokens": 0,
    "total_tokens": 0,
    "completion_tokens_details": {
      "accepted_prediction_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0,
      "rejected_prediction_tokens": 0
    },
    "prompt_tokens_details": {
      "audio_tokens": 0,
      "cached_tokens": 0
    }
  }
}

Returns Examples

200 example

{
  "id": "id",
  "choices": [
    {
      "finish_reason": "stop",
      "index": 0,
      "logprobs": {
        "content": [
          {
            "token": "token",
            "bytes": [
              0
            ],
            "logprob": 0,
            "top_logprobs": [
              {
                "token": "token",
                "bytes": [
                  0
                ],
                "logprob": 0
              }
            ]
          }
        ],
        "refusal": [
          {
            "token": "token",
            "bytes": [
              0
            ],
            "logprob": 0,
            "top_logprobs": [
              {
                "token": "token",
                "bytes": [
                  0
                ],
                "logprob": 0
              }
            ]
          }
        ]
      },
      "message": {
        "content": "content",
        "refusal": "refusal",
        "role": "assistant",
        "annotations": [
          {
            "type": "url_citation",
            "url_citation": {
              "end_index": 0,
              "start_index": 0,
              "title": "title",
              "url": "url"
            }
          }
        ],
        "audio": {
          "id": "id",
          "data": "data",
          "expires_at": 0,
          "transcript": "transcript"
        },
        "function_call": {
          "arguments": "arguments",
          "name": "name"
        },
        "tool_calls": [
          {
            "id": "id",
            "function": {
              "arguments": "arguments",
              "name": "name"
            },
            "type": "function"
          }
        ]
      }
    }
  ],
  "created": 0,
  "model": "model",
  "object": "chat.completion",
  "service_tier": "auto",
  "system_fingerprint": "system_fingerprint",
  "usage": {
    "completion_tokens": 0,
    "prompt_tokens": 0,
    "total_tokens": 0,
    "completion_tokens_details": {
      "accepted_prediction_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0,
      "rejected_prediction_tokens": 0
    },
    "prompt_tokens_details": {
      "audio_tokens": 0,
      "cached_tokens": 0
    }
  }
}