# Don't tell Sonnet 5.5 to minimize tool calls

> On Sonnet 5.5, 'minimize tool calls' makes it answer from training data when a search would catch what changed. Delete the line; say when to check sources.

URL: https://bartlomiejkrupa.dev/notes/dont-discourage-tool-calls/
Category: rule | Updated: 2026-09-30
Summary: On Sonnet 5.5, 'minimize tool calls' makes it answer from training data when a search would catch what changed. Delete the line; say when to check sources.

**Don't discourage tool calls** is the rule that a Claude Sonnet 5.5 prompt should never tell the model to avoid its tools. A tool call is the model asking your app to run a function, such as a web search or a file read. Anthropic's Sonnet 5.5 prompting guide names the symptom: on chat and knowledge-work tasks, the model sometimes answers from what it learned in training when a web search would show that something has changed - such as what is allowed, required, or charged.

## Rule

1. Search your prompts, `CLAUDE.md`, skills and subagent prompts for "only use tools when strictly necessary", "minimize tool calls", or any wording that makes a tool call sound like a cost.
2. Delete it. The guide lists this as the first step, before adding anything.
3. If the product gives the model a search tool, add the guide's replacement line, which says when to search:

```text
Use the search tool to check specifics that may have changed since your training, such as what is allowed, required or charged, even when you feel confident. For researched work such as a report or a comparison, gather current sources rather than writing from your training knowledge.
```

No search tool in the setup: deleting the line is the whole fix. Don't add a replacement that promises lookups the model can't make.

The guide says this matters most for research and support products, where answers depend on current details.

Found by an audit, not by guessing: [Claude 5.5 prompt audit: the bad lines weren't there](/articles/claude-5-5-prompt-audit).

Sources:
- Prompting Claude Sonnet 5.5: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-sonnet-5-5