The company hosting a model can affect whether an AI application successfully calls its tools. OpenRouter says its Exacto endpoints, introduced in October 2025, route requests to selected providers using evidence about tool-call reliability. Its checks include whether a response names an available tool and supplies arguments in the required format.
Provider selection also considers how often models attempt tool calls and customer provider preferences. The intended benefit is fewer integration failures when an assistant must take actions through software. These checks concern tool useA model's ability to call external functions — run code, search the web, edit files — instead of only generating text.Full definition →: a correctly formatted call can still be the wrong action, so format accuracy alone does not establish task success.
Terms in this piece · Glossary
tool use — A model's ability to call external functions — run code, search the web, edit files — instead of only generating text.
benchmark — A standard public test set for comparing AI models — the shared scoreboards behind every "model X beats model Y" claim.
