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Providers

Alibaba Anthropic Bedrock Cerebras Cohere DeepSeek Fireworks Google Groq Meta MiniMax Mistral Moonshot AI NVIDIA OpenAI Opencode Go Perplexity Thinking Machines Vertex xAI Xiaomi Z.ai

Providers

Alibaba Anthropic Bedrock Cerebras Cohere DeepSeek Fireworks Google Groq Meta MiniMax Mistral Moonshot AI NVIDIA OpenAI Opencode Go Perplexity Thinking Machines Vertex xAI Xiaomi Z.ai
OpenAI Responses API Subscription Retired 3 params

OpenAI GPT-5.3 Codex Spark (subscription) API parameters

These are the API parameters modelparams.dev tracks for OpenAI GPT-5.3 Codex Spark on Responses API through a subscription — the settings you send in a request. 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.

This model is retired.

After the parameter count instead — how many weights GPT-5.3 Codex Spark has? That's a different number, and we don't track it. Here's the difference.

Reasoning 2 params
Parameter Type Default Description Condition
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
Parameter Type Default Description Condition
Verbosity
text.verbosity 		enum (low | medium | high) "medium" Controls how concise or detailed the model's final text response should be. —

OpenAI GPT-5.3 Codex Spark API parameters in brief

OpenAI GPT-5.3 Codex Spark on Responses API via subscription documents 3 API parameters, grouped by what they control:

Frequently asked questions

Which API parameters does OpenAI GPT-5.3 Codex Spark (subscription) support?
OpenAI GPT-5.3 Codex Spark (subscription) accepts 3 API parameters in the request body: reasoning.effort, reasoning.summary, text.verbosity.

Resources

All OpenAI models Glossary Full catalog

GPT-5.3 Codex Spark — JSON

The full model definition as served by the API. Copy it or open the endpoint directly.

/api/v1/models/openai/gpt-5.3-codex-spark-subscription.json 
{
  "$schema": "https://modelparams.dev/api/v1/schema.json",
  "provider": "openai",
  "authType": "subscription",
  "apiSurface": "openai-responses",
  "model": "gpt-5.3-codex-spark",
  "status": "retired",
  "params": [
    {
      "path": "reasoning.effort",
      "label": "Reasoning effort",
      "description": "Controls how much reasoning the model should perform before producing an answer.",
      "group": "reasoning",
      "type": "enum",
      "default": "medium",
      "values": [
        "minimal",
        "low",
        "medium",
        "high",
        "xhigh"
      ]
    },
    {
      "path": "reasoning.summary",
      "label": "Reasoning summary",
      "description": "Controls the level of reasoning summary returned with the response.",
      "group": "reasoning",
      "type": "enum",
      "default": "auto",
      "values": [
        "auto",
        "concise",
        "detailed",
        "none"
      ]
    },
    {
      "path": "text.verbosity",
      "label": "Verbosity",
      "description": "Controls how concise or detailed the model's final text response should be.",
      "group": "output_format",
      "type": "enum",
      "default": "medium",
      "values": [
        "low",
        "medium",
        "high"
      ]
    }
  ]
}

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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 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.

If you only need the params for one model contract, use the providerless endpoint. Subscription contracts are model slugs with -subscription. 

curl https://modelparams.dev/api/v1/models/openai/gpt-5.5.json
curl https://modelparams.dev/api/v1/models/openai/gpt-5.5-subscription.json

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