openai

openai("gpt-5.5") needs no limits: they come from spec/models/openai.v1.json, read from OpenAI's model pages. Pass it as agent({model: openai("gpt-5.5")}).

Import from @threads/openai (TypeScript) or threads.openai (Python).

function openai(model: string, options?: {
  maxInputTokens?: number;
  maxOutputTokens?: number;
  maxTokens?: number;
  params?: JsonObject;
  price?: Price;
  hostedTools?: readonly JsonObject[];
  apiKey?: string | Secret;
  baseUrl?: string;
  fetch?: (input: string | URL | Request, init?: RequestInit) => Promise<Response>;
}): Model

Parameters

modelstringrequired

The provider's exact model id. Matched against spec/models/openai.v1.json by string equality only; a snapshot id keeps a long-lived thread on one model.

maxInputTokens / max_input_tokensnumber

The most input tokens one request may carry; compaction and the input billing bound use it. Pinned as policy.models[].context_window. Omitted: the catalog entry's value; a model id the catalog doesn't list needs it.

maxOutputTokens / max_output_tokensnumber

The most output tokens the model can produce in one response. Pinned in policy.models. Omitted: the catalog entry's value; a model id the catalog doesn't list needs it.

maxTokens / max_tokensnumber

The per-request output cap, pinned as params.max_tokens (the pinned prompt prefix) and sent as max_output_tokens. Output-token budgets read it. Omitted: min(8192, max_output_tokens); a long answer continues in a new request. Above max_output_tokens is invalid_config.

paramsJsonObject

Other Responses API request fields (temperature, reasoning and the like), pinned in the system prompt. A field the adapter derives from the render, or the cap, is invalid_config. Omitted: none.

pricePrice

Nano-currency units per token, pinned in policy.models; a cost budget needs it. Omitted: cost is unknown.

hostedTools / hosted_toolsreadonly JsonObject[]

Provider-executed tools, sent as given and pinned in the system prompt: web search (web_search, with an optional _preview and date) only; any other is hosted_tool_unsupported. Omitted: none.

apiKey / api_keystring | Secret

The API key: a secret() or a string. Omitted: secret("OPENAI_API_KEY"). Resolved on the host at setup (check() or the first run); unset is missing_secret naming the option and the variable. Never pinned or logged.

baseUrl / base_urlstring

The API base URL. Omitted: the SDK's default endpoint.

fetch(input: string | URL | Request, init?: RequestInit) => Promise<Response>

TypeScript only. Seam: the fetch the SDK sends through (a proxy, a test server); the run's fence wraps it either way. Omitted: globalThis.fetch.

Returns

Model

Throws ConfigError with one of these codes: hosted_tool_unsupported, invalid_config, missing_secret.

Parameters

Returns

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