# Tools give data and actions

Tools do two jobs: fetch data the model doesn't have (an order status) and take actions it can't take (create a Jira ticket).

AI developers · Part 03: Tool calling · Card 10 of 10 · Last updated 2026-10-13

## Analogy

GET routes and POST routes. Reading is cheap and safe; writing deserves more care.

## In an agent

Read tools can run freely. Write tools (delete, refund, send email) usually need validation and a human approval step.

## Questions people ask

### What kinds of tools does an agent need?

Two kinds. Read tools fetch data the model does not have, like an order status or a document search. Write tools take actions it cannot take, like creating a ticket or sending an email. Read tools are low risk. Write tools change the world, so they need more checks.

### Should write tools need human approval?

Usually, yes, for anything that is hard to undo or reaches customers: deleting data, refunds, payments and outgoing emails. The agent proposes the action and a person approves it. Read tools can run freely. This keeps the damage small if the agent is confused or tricked by injected text.

## Related concepts

- [What a tool is](https://studyvisually.com/learn/tech/ai-developers/tool-calling/what-a-tool-is)
- [Function schema](https://studyvisually.com/learn/tech/ai-developers/tool-calling/function-schema)
- [Tool description](https://studyvisually.com/learn/tech/ai-developers/tool-calling/tool-description)
- [The tool_calls reply](https://studyvisually.com/learn/tech/ai-developers/tool-calling/tool-calls-response)

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