What Are Tools Anyway? A Survey of Tool Use in LLMs
This survey establishes a formal definition of tools as "external programs used by LMs" and systematizes when, why, and how tool-use improves LLM performance.
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Formal definition: Tools are any external program invoked by an LM to augment its capabilities, unifying function calling, retrieval, code execution, and web browsing under one framework.
Taxonomy: Organizes tool-use scenarios and techniques so that prior work can be compared on common axes (trigger, invocation, integration, supervision).
Cost-benefit analysis: Empirically measures compute and latency overhead of tool use versus accuracy gain across benchmarks, revealing clear tradeoffs rather than free lunches.
Open directions: Identifies challenges in tool selection, generalization to unseen tools, and evaluation methodology as the main bottlenecks for the next wave of tool-augmented LLMs.