GET

/v1/schemas/openai/chat/completions

Accept:

kind inputactivity chathash c2fadeb7…extracted Jul 6, 2026version currentsource upstream spec ↗

Request body

18 properties · 2 required · 2 $defs

property	type	description	constraints
model*	string \| enum	ID of the model to use. You can use the [List models](/docs/api-reference/models/list) API to see all of your available models, or see our [Model overview](/docs/models) for descriptions of them.
prompt*	string \| string[] \| integer[] \| …	The prompt(s) to generate completions for, encoded as a string, array of strings, array of tokens, or array of token arrays.	default: "<\|endoftext\|>"
best_of	integer	Generates `best_of` completions server-side and returns the "best" (the one with the highest log probability per token). Results cannot be streamed.	0 ≤ n ≤ 20 · default: 1
echo	boolean	Echo back the prompt in addition to the completion	default: false
frequency_penalty	number	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.	-2 ≤ n ≤ 2 · default: 0
logit_bias	object	Modify the likelihood of specified tokens appearing in the completion.	default: null
logprobs	integer	Include the log probabilities on the `logprobs` most likely output tokens, as well the chosen tokens. For example, if `logprobs` is 5, the API will return a list of the 5 most likely tokens. The API will always return the `logprob` of the sampled token, so the…	0 ≤ n ≤ 5 · default: null
max_tokens	integer	The maximum number of [tokens](/tokenizer) that can be generated in the completion.	n ≥ 0 · default: 16
n	integer	How many completions to generate for each prompt.	1 ≤ n ≤ 128 · default: 1
presence_penalty	number	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.	-2 ≤ n ≤ 2 · default: 0
seed	integer	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.	format: int64
stop	string \| string[]	Not supported with latest reasoning models `o3` and `o4-mini`.	default: null
stream	boolean	Whether to stream back partial progress. If set, tokens will be sent as data-only [server-sent events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#Event_stream_format) as they become available, with the stream t…	default: false
stream_options	object	Options for streaming response. Only set this when you set `stream: true`.	default: null · nullable
suffix	string	The suffix that comes after a completion of inserted text.	default: null
temperature	number	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.	0 ≤ n ≤ 2 · default: 1
top_p	number	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.	0 ≤ n ≤ 1 · default: 1
user	string	A unique identifier representing your end-user, which can help OpenAI to monitor and detect abuse. [Learn more](/docs/guides/safety-best-practices#end-user-ids).

Validate a payload

before you spend tokens

shell

$ curl -X POST https://modelschemas.com/v1/validate \
    -d '{"provider":"openai","endpointId":"completions","payload":{…}}'
→ {"valid": false, "errors": [{"path": "#", "keyword": "required", …}]}