Landmark 18 stops to get here · leads to 1

Tool Use

LLMs learning to call external tools, APIs, or functions to extend capabilities beyond text generation (calculators, search, code execution).

Your route here

18 stops · basics first
  1. Natural Language Processing ✓ understood

    The field of AI that lets computers read, interpret, translate and generate human language, from spam filters and search to chatbots.

  2. Token ✓ understood

    The basic unit of text that a language model processes, typically representing a word, subword, or character. Tokens are the fundamental building blocks for LLM input and output.

  3. Tokenization ✓ understood

    Splitting text into tokens, usually subword pieces, and mapping each to an integer ID so a language model can process it.

  4. Language Modeling ✓ understood

    Learning probability distributions over sequences of words to predict what comes next.

  5. Dataset ✓ understood

    A collection of data examples used for training, validating, or testing machine learning models.

  6. Training ✓ understood

    The process of fitting a model to data by repeatedly measuring how wrong its outputs are and adjusting its parameters to reduce that error.

  7. Machine Learning ✓ understood

    Building systems that learn patterns from data instead of following hand-written rules, getting better at a task as they see more examples.

  8. Unsupervised Learning ✓ understood

    Learning from unlabeled data to discover hidden patterns, structures, or relationships without explicit target outputs.

  9. Self-Supervised Learning ✓ understood

    Learning representations from unlabeled data by creating supervised tasks from the data itself (masked prediction, contrastive learning).

  10. Pre-training ✓ understood

    Training a model on a large dataset (often self-supervised) before fine-tuning on specific tasks, enabling transfer learning.

  11. Feature ✓ understood

    A single measurable property of an example, such as a house's floor area or how many links an email contains, used as an input to a model.

  12. Neural Network ✓ understood

    A computational model inspired by biological neural networks, consisting of interconnected nodes (neurons) organized in layers that process information through weighted connections.

  13. Deep Learning ✓ understood

    A subset of machine learning that uses neural networks with multiple layers (deep neural networks) to learn hierarchical representations of data.

  14. Representation Learning ✓ understood

    Learning useful features or representations of data automatically, rather than hand-crafting them.

  15. Embedding ✓ understood

    A list of numbers (a vector) that represents a word, sentence, image or other item, learned so that similar items end up close together.

  16. Attention Mechanism ✓ understood

    A technique that lets a neural network weigh every part of its input when producing each output, focusing on the parts most relevant at that step.

  17. Transformer ✓ understood

    A neural network architecture, introduced in 2017, built from stacked self-attention and feed-forward layers; the basis of nearly every modern large language model.

  18. Large Language Model ✓ understood

    A neural network, almost always a transformer, trained on vast amounts of text to predict the next token, which lets it write, answer, summarize and follow instructions.

  19. Tool Use · you are here ✓ understood

Picture it

  1. 01 User asks a question "What's 17% of 2,340?"
  2. 02 Model emits a tool call Structured name + arguments, e.g. JSON
  3. 03 App runs the tool Calculator, search, code, API
  4. 04 Result returns to model Added to the context as a tool result
  5. 05 Model answers Grounded in the tool's output
Notice that the model doesn't run the tool itself: it only asks, your code executes, and the result is fed back into its context.

Where it sits

Tool Use

Leads to

AI Agent

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In the research

All papers →

11 papers that build on Tool Use ; showing 5, canon first.

Canon · 2022 ReAct: Synergizing Reasoning and Acting in Language Models The think–act–observe loop in ReAct is the skeleton of nearly every LLM agent and coding harness today. Frontier · Dec 2025 · 671 citations DeepSeek-V3.2: Pushing the Frontier of Open Large Language Models It shows an open model competing with the best closed ones on reasoning while getting cheaper to run. Frontier · Feb 2026 · 174 citations SkillsBench: Benchmarking How Well Agent Skills Work Across Diverse Tasks It is the first careful evidence that skills work, and that smaller models with good skills can match bigger ones. Frontier · Sep 2025 · 139 citations SimpleTIR: End-to-End Reinforcement Learning for Multi-Turn Tool-Integrated Reasoning A one-idea fix that makes multi-turn tool-using RL trainable. Frontier · Aug 2025 · 101 citations WebWatcher: Breaking New Frontier of Vision-Language Deep Research Agent Deep-research agents have been text-only; this extends them to the visual web.