It's counterintuitive, but using a more expensive, intelligent model like Opus 4.5 can be cheaper than smaller models. Because the smarter model is more efficient and requires fewer interactions to solve a problem, it ends up using fewer tokens overall, offsetting its higher per-token price.

When evaluating AI agents, the total cost of task completion is what matters. A model with a higher per-token cost can be more economical if it resolves a user's query in fewer turns than a cheaper, less capable model. This makes "number of turns" a primary efficiency metric.

Newer AI models may have low per-token prices but are often "token hungry," requiring more tokens to complete a task. This can make them more expensive overall. The true measure of economic viability is the final cost-per-task, not the misleading per-token price.

Despite a higher price per token, Fable 5 can be more cost-effective in practice. Its ability to solve complex problems correctly on the first try ("one-shot") eliminates the significant token and time costs associated with iterative reprompting, making it cheaper for ambitious projects that require high accuracy.

The binary distinction between "reasoning" and "non-reasoning" models is becoming obsolete. The more critical metric is now "token efficiency"—a model's ability to use more tokens only when a task's difficulty requires it. This dynamic token usage is a key differentiator for cost and performance.

A model with a low per-token price can be more expensive if it's inefficient, verbose, or requires multiple attempts ('overthinking'). The actual invoice depends on the total tokens needed to complete a task, making token efficiency a hidden multiplier that savvy enterprises are now tracking to determine the true cost.

In complex, multi-step tasks, overall cost is determined by tokens per turn and the total number of turns. A more intelligent, expensive model can be cheaper overall if it solves a problem in two turns, while a cheaper model might take ten turns, accumulating higher total costs. Future benchmarks must measure this turn efficiency.

An AlphaSense study revealed that models with a higher price-per-token, like GPT 5.6 Sol, can complete tasks for a lower total cost than cheaper Chinese models. This is because their superior efficiency requires fewer tokens to achieve a higher-quality result, making simple price comparisons misleading.

An AI model might have a low cost per token but be 'token hungry,' requiring more tokens to complete a task. This makes it more expensive overall than a model with a higher per-token cost but greater efficiency. Evaluating models on a 'cost per task' basis provides a more accurate ROI.