modelparams.dev
OpenAI Subscription 3 params

OpenAI Gpt 5.3 Codex (subscription) parameters

These are the parameters modelparams.dev tracks for OpenAI Gpt 5.3 Codex when you reach it through a subscription rather than an API key. Each row gives the type, default, valid range or values, and the conditions that gate it. It's the same data the JSON API serves.

Parameter Type Default Description Condition
Reasoning · 2 params
Reasoning effort
reasoning.effort 		enum (minimal | low | medium | high | xhigh) "medium" Controls how much reasoning the model should perform before producing an answer. —
Reasoning summary
reasoning.summary 		enum (auto | concise | detailed | none) "auto" Controls the level of reasoning summary returned with the response. —
Output · 1 param
Verbosity
text.verbosity 		enum (low | medium | high) "medium" Controls how concise or detailed the model's final text response should be. —
This model as JSON All OpenAI models Parameter glossary Full catalog

Other OpenAI models

Chatgpt 4o Latest Gpt 3.5 Turbo Gpt 4 Turbo Gpt 4 Turbo 2024.04 09 Gpt 4.1 Gpt 4.1 Mini Gpt 4.1 Nano Gpt 4o 2024.11 20 Gpt 5 Gpt 5 Chat Latest Gpt 5 Mini Gpt 5 Nano Gpt 5.1 Gpt 5.1 Codex subscription Gpt 5.1 Codex Max subscription Gpt 5.2 Gpt 5.2 subscription Gpt 5.2 Codex subscription Gpt 5.3 Codex Spark subscription Gpt 5.4 Gpt 5.4 subscription Gpt 5.4 Mini Gpt 5.4 Mini subscription Gpt 5.5 Gpt 5.5 subscription GPT-4o GPT-4o mini o1 O1 Preview o1-mini o3 o3-mini o4-mini

How to use

Building with an AI agent? Hit Copy to grab this whole guide as Markdown and paste it in — or point your agent straight at /llms.txt.

modelparams.dev is an open, community-maintained catalog of LLM model parameters. Each entry shows the knobs you can turn — type, default, range, and the conditions that gate it.

The same model accessed via an API key and via a subscription usually exposes a different set of parameters. We list both as separate entries so the data stays honest.

Catalog API

The full catalog is static JSON, CORS-enabled, served from the edge.

curl https://modelparams.dev/api/v1/models.json

Each entry is keyed by provider/model for API-key variants; subscription variants append -subscription.

Single model

curl https://modelparams.dev/api/v1/models/anthropic/claude-opus-4-7.json
curl https://modelparams.dev/api/v1/models/anthropic/claude-opus-4-7-subscription.json

JSON Schema

Every entry validates against a JSON Schema you can use in your editor or pipeline. 

curl https://modelparams.dev/api/v1/schema.json

Add this header to any YAML you author for autocomplete in VS Code: 

# yaml-language-server: $schema=https://modelparams.dev/api/v1/schema.json

Logos

Provider logos are available at /assets/logos/{provider}.svg where {provider} is the provider slug. They use currentColor so they inherit your text color. 

curl https://modelparams.dev/assets/logos/anthropic.svg

Logos are sourced from the models.dev repo (MIT) and used under nominative fair use.

Contribute

The data lives in YAML under models/{provider}/{model}-{auth}.yaml in the GitHub repo. Open a PR; CI validates against the schema and rebuilds.

Edit on GitHub MIT licensed