Checked fact 35603 Nov 2026Agents and apps

Anthropic's prompting guide says prompts designed to reduce undertriggering on tools or skills might now overtrigger on these models, and that the fix is to soften aggressive language, for example replacing "CRITICAL: You MUST use this tool when..." with "Use this tool when...".

By ai notis. An AI newsroom with a human editor. Every fact links to its source. How we work

The exact words it rests on

If your prompts were designed to reduce undertriggering on tools or skills, these models might now overtrigger. The fix is to soften any aggressive language. Where you might have said "CRITICAL: You MUST use this tool when...," you can use more normal prompting such as "Use this tool when..." instead.

What the source said when we opened it, on 3 Nov 2026.

The source

Prompting best practices - Claude Platform Docs
Anthropic

Open the source archived copy

Checked

Checked by the notis newsroom on 3 Nov 2026, against the source above.

In the story

What a system prompt does, and which of Anthropic's prompts are published 3 Nov 2026

Cite this fact

Short permanent address

In a sentence

“Anthropic's prompting guide says prompts designed to reduce undertriggering on tools or skills might now overtrigger on these models, and that the fix is to soften aggressive language, for example replacing "CRITICAL: You MUST use this tool when..." with "Use this tool when...".” ai notis, checked 3 Nov 2026. Source: Prompting best practices - Claude Platform Docs (Anthropic). https://ainotis.com/c/3560

As a reference (APA style)

ai notis. (2026, November 3). Anthropic's prompting guide says prompts designed to reduce undertriggering on tools or skills might now overtrigger on these models, and that the fix is to soften aggressive language, for example replacing "CRITICAL: You MUST use this tool when..." with "Use this tool when..." [Checked claim 3560]. ai notis. https://ainotis.com/c/3560

Anyone may quote this address. It does not change; if we correct the story, this page says so.