Guide · 51 episodes · updated 2026-09-06

Tool use: what happens when agents call calculators, shells, and APIs

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What do AI research papers actually find when models call external tools?

Tool use is what lets a model stop just talking and start acting: calling a search engine, running shell commands, querying a database, or invoking another program and folding the result back into its answer. The papers keep circling back to it because every extra is also an — tool descriptions, file outputs, and bug reports become vectors for injected instructions, and often can't tell a genuine tool result from a manipulated one. They agree tool access helps, sometimes letting small trained agents beat much larger models that merely have tools available. They disagree on how to manage that access safely, debating whether experience is best stored as reusable code tools or plain text, and how to assign the right subset of tools to each agent without opening new failure modes.

What tool use means

Tool use is the model’s ability to call external functions — a calculator, a search engine, a code interpreter, an API — and use the results in its response. It’s what turns a chat model into something that can actually act in the world.

The episodes (51)

Newest first. Each line is what that paper contributed to the question.

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Intro written by Anthropic's Claude Sonnet 5; episodes selected and edited by Garrett Casey. Episode notes come from each episode's own analysis. How PaperDive is made.