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Exacto is a virtual model variant that explicitly applies quality-first provider sorting. When you add :exacto to a model slug, OpenRouter prefers providers with stronger tool-calling quality signals for that model instead of using the default price-weighted ordering.

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Using the Exacto Variant

Add :exacto to the end of any supported model slug. This is a shortcut for setting the provider sort to Exacto on that model. 
import { OpenRouter } from '@openrouter/sdk';

const openRouter = new OpenRouter({
  apiKey: process.env.OPENROUTER_API_KEY,
});

const completion = await openRouter.chat.send({
  model: "moonshotai/kimi-k2-0905:exacto",
  messages: [
    {
      role: "user",
      content: "Draft a concise changelog entry for the Exacto launch.",
    },
  ],
  stream: false,
});

console.log(completion.choices[0].message.content);
You can still supply fallback models with the models array. Any model that carries the :exacto suffix will request Exacto sorting when it is selected.

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What Is the Exacto Variant?

Exacto is a routing shortcut for quality-first provider ordering. Unlike standard routing, which primarily favors lower-cost providers, Exacto prefers providers with stronger signals for tool-calling reliability and deprioritizes weaker performers.

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Why Use Exacto?

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Why We Built It

Providers serving the same model can vary meaningfully in tool-use behavior. Exacto gives you an explicit, request-level way to prefer higher-quality providers when you care more about tool-calling reliability than the default price-weighted route. Exacto is useful for quality-sensitive, agentic workflows where tool-calling accuracy and reliability matter more than raw cost efficiency.

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How Exacto Works

Exacto uses the same provider-ranking signals as Auto Exacto, but applies them explicitly because you chose the :exacto suffix. We use three classes of signals:
  • Tool-calling success and reliability from real traffic — see How Tool-Calling Success Rate Is Measured for the underlying methodology
  • Provider performance metrics such as throughput and latency
  • Benchmark and evaluation data as it becomes available
Providers with strong track records are moved toward the front of the list. Providers with limited data are kept behind well-established performers, and providers with poor quality signals are deprioritized further.

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Exacto vs. Auto Exacto

  • Auto Exacto runs automatically on tool-calling requests and requires no model suffix.
  • :exacto is the explicit shortcut when you want to request the Exacto sorting mode directly on a specific model slug.
If you explicitly sort by price, throughput, or latency, that explicit sort still takes precedence.

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Supported Models

Exacto is a virtual variant and is not backed by a separate endpoint pool. It can be used anywhere provider sorting is meaningful, especially on models with multiple compatible providers. In practice, Exacto is most useful on models that:
  • Support tool calling
  • Have multiple providers available on OpenRouter
  • Show meaningful provider variance in tool-use reliability
If you have feedback on the Exacto variant, please fill out this form: https://openrouter.notion.site/2932fd57c4dc8097ba74ffb6d27f39d1?pvs=105