---
title: "Ultrathink"
url: https://perrotta.dev/2025/05/ultrathink/
last_updated: 2026-07-29
---


Simon Willison,
[Ultrathink](https://simonwillison.net/2025/Apr/19/claude-code-best-practices/)
([via](https://news.ycombinator.com/item?id=43739997)):

> We recommend using the word "think" to trigger extended thinking mode, which
> gives Claude additional computation time to evaluate alternatives more
> thoroughly. These specific phrases are mapped directly to increasing levels of
> thinking budget in the system: "think" < "think hard" < "think harder" <
> "ultrathink." Each level allocates progressively more thinking budget for
> Claude to use.

A prompt I used recently:

> How can I leverage [`kustomize`](https://kustomize.io/) modules (e.g.
> components or replacements) to reduce code duplication in this repository?
> Ultrathink and suggest some ideas.

🤖