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Plain-language AI glossary

Term 73TechniquesMeaning / context / connections

Techniques / Definition

Tool Use (AI)

The capability of AI models to interact with external tools, APIs, and systems by generating structured function calls based on natural language instructions.

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MeaningThe one-sentence definition.

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ContextHow the idea works in practice.

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UsesWhere the concept becomes useful.

01 / Plain-language context

How Tool Use (AI) works.

Tool use is what transforms an LLM from a text generator into an AI that can take actions in the real world. Without tools, an LLM can only produce text. With tools, it can: search the web, query databases, send emails, create calendar events, execute code, and interact with any system that has an API.

The mechanism: (1) You define available tools as JSON schemas (function name, description, parameters). (2) The user sends a message. (3) The model decides whether to call a tool and generates the function call with arguments. (4) Your code executes the function and returns the result to the model. (5) The model uses the result to generate its final response.

All major providers support this: OpenAI calls it "function calling," Anthropic calls it "tool use," Google calls it "function calling." The Model Context Protocol (MCP) is an emerging standard for sharing tool definitions across AI systems. Production considerations: validate all tool arguments (the model can generate invalid inputs), implement timeouts for external calls, handle tool failures gracefully, and log all tool invocations for debugging and auditing.

02 / Practical uses

Where it helps.

  1. 01AI assistants that book appointments
  2. 02Database querying from natural language
  3. 03Automated report generation
  4. 04Smart home control via voice
  5. 05Multi-step workflow automation
03 / Keep exploring
Function Calling (Tool Use)An AI capability where the model can decide to invoke external functions or APIs based on the conversation context.AI AgentAn AI system that can autonomously plan, reason, use tools, and take actions to accomplish goals with minimal human intervention.MCP (Model Context Protocol)An open standard by Anthropic that provides a universal way for AI models to connect to external data sources and tools.Agentic WorkflowA multi-step AI process where an LLM autonomously plans, executes, and iterates on tasks using tools and feedback loops.