@ai-sdk/provider/src/language-model/v2/language-model-v2-usage.ts

/**
 * Usage information for a language model call.
 *
 * If your API return additional usage information, you can add it to the
 * provider metadata under your provider's key.
 */
export type LanguageModelV2Usage = {
  /**
   * The number of input (prompt) tokens used.
   */
  inputTokens: number | undefined;

  /**
   * The number of output (completion) tokens used.
   */
  outputTokens: number | undefined;

  /**
   * The total number of tokens as reported by the provider.
   * This number might be different from the sum of `inputTokens` and `outputTokens`
   * and e.g. include reasoning tokens or other overhead.
   */
  totalTokens: number | undefined;

  /**
   * The number of reasoning tokens used.
   */
  reasoningTokens?: number | undefined;

  /**
   * The number of cached input tokens.
   */
  cachedInputTokens?: number | undefined;
};