We have a following response data model where EntityA contains field_a of Array type with constraints on min and max item count: { "$defs":{ "GenerateResponse":{ "items":{ "anyOf":[ { "$ref":"#/$defs/EntityA" } …

Hi @vmalyi and welcome to the community! minItems and maxItems are currently not supported, see here . I am not sure “when” they will be supported - perhaps one of the OpenAI staff can comment. I found that I can to a certain degree control this via my prompt or by providing this as a description …

They are now, yes, took a while :slight_smile:

Thanks for following up on this. I will update the solution to make this clear to anyone else reading this.

"min-" & "maxItems" are not supported in Structured Output

API

Tamique_de_Brito November 19, 2025, 6:20pm 3

I think they are now supported, see here

1 Like

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"min-" & "maxItems" are not supported in Structured Output

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