# Tool use

Concept · [Building with AI](https://ecosystem.samcarlton.com/ai)

Also called: tools, tool calling, tool call, function calling, function call, tool

A way for a model to ask the software around it to run a defined action, such as a search or a [database](https://ecosystem.samcarlton.com/database) lookup, and send back the result. It is also called function calling. The model decides when to ask, and the software does the running.

**For example:** A user asks an assistant, 'What did order 1042 cost?' The [model requests](https://ecosystem.samcarlton.com/model-provider-request) the order-lookup tool, the app runs it, and the model writes the answer from the result.

## Connects to (16)

- [AI agent](https://ecosystem.samcarlton.com/ai-agent): An AI tool that does more than answer a question.
- [MCP](https://ecosystem.samcarlton.com/terms/mcp): Model Context Protocol.
- [API](https://ecosystem.samcarlton.com/terms/api): Application programming interface.
- [Model](https://ecosystem.samcarlton.com/model): The trained system at the center of an AI product.
- [Harness](https://ecosystem.samcarlton.com/harness): The software wrapped around an AI model that turns it into a working agent.
- [Turn](https://ecosystem.samcarlton.com/turn): One round of a conversation with an agent: you send a message, and the agent works until it hands control back to you.
- [Agent environment](https://ecosystem.samcarlton.com/agent-environment): Everything outside the agent's own software that it can look at or change: your files, terminal, browser, databases and connected services.
- [Filesystem](https://ecosystem.samcarlton.com/filesystem): The files and folders on a computer.
- [Permission request](https://ecosystem.samcarlton.com/permission-request): The pause where an agent asks before it takes an action its permission mode does not allow on its own.
- [Tool result](https://ecosystem.samcarlton.com/tool-result): What comes back to the model after it uses a tool: a file's contents, the output of a command, a search result or an error.
- [Subagent](https://ecosystem.samcarlton.com/subagent): A second agent that the main agent starts to handle one piece of a job in its own separate session.
- [OpenAPI](https://ecosystem.samcarlton.com/openapi): A standard format for describing what an API offers: its addresses, what each one expects and what it returns.
- [Agent loop](https://ecosystem.samcarlton.com/agent-loop): The repeating cycle that makes an AI agent work: the model decides on a step, calls a tool, reads the result and decides the next step…
- [Claude Cowork](https://ecosystem.samcarlton.com/claude-cowork): Anthropic's name for Claude carrying out multi-step tasks across a person's files and tools, such as organizing folders or assembling a…
- [FunctionGemma](https://ecosystem.samcarlton.com/functiongemma): A small Gemma model from Google tuned to turn plain requests into function calls, so an app or device can act on what a person asks.
- [OpenClaw](https://ecosystem.samcarlton.com/openclaw): An open-source AI agent that a person runs on their own computer or server.

Map view: https://ecosystem.samcarlton.com/tool-use