The Short Answer
ultracode is a Claude Code switch. When it is on, Claude decides for each task whether to bring in a group of agents to work at the same time, without waiting for you to ask.
What ultracode Does
A workflow is a script Claude writes for a task to coordinate many subagents (small helpers the main Claude sends out to handle individual tasks). For details, see the companion article, What Are Claude Code Dynamic Workflows?.
Normally, you have to ask for a workflow yourself. With ultracode on, Claude decides whether a task is worth using one for. The tradeoff is that every task uses more tokens and takes longer, and subscription plans also reach their usage limits sooner.
What Changed in Late September 2026
Since the late September 2026 update, turning on ultracode with /effort no longer raises effort to xhigh. Your effort stays the same, and ultracode stays on if you change effort afterward.
Earlier articles describe the old behavior, including Penchan’s May article about Opus 4.8, which has since been updated. If you want workflows to do more careful work, raise effort yourself. For help choosing effort, see How to Choose Claude Code Effort.
How to Turn It On or Off
- For one task only: Type
ultracodeyourself in an interactive prompt. The session’s effort stays the same. - For this session: Enter
/effort ultracode. - By default for every future session: Add
"ultracode": trueto~/.claude/settings.jsonto turn it on by default (project settings may override this).
To turn it off, enter /effort ultracode off to disable it for this session. To cancel the default for every session, change true to false in the settings file. To disable keyword activation, turn off Ultracode keyword trigger in /config. Workflows must be enabled (Pro users need to turn them on in /config first), and the model must support xhigh.
Similar Names, Different Jobs
| Feature | What it does | Who decides | How long it applies |
|---|---|---|---|
| effort | Adjusts how deeply the model thinks at each step | You | Depends on how you set it |
| ultrathink | A keyword that asks Claude to think more deeply for that turn | You | One turn |
| Requesting a workflow yourself | Turns the task into a script that coordinates many subagents | You | That task |
| ultracode | Claude decides whether a task is worth using a workflow for | Claude (you control the switch) | The entire session, or one task when triggered by the keyword |
| ultrareview | A deep, cloud-based code review, billed separately after the one-time free uses for Pro and Max are used up | You | One review |
The three names that start with ultra are easiest to mix up: ultrathink asks Claude to think more deeply for one turn, ultracode lets Claude decide whether to bring in a group of agents, and ultrareview is a cloud code review that you start yourself.
When to Turn It On
- Your whole session involves large, separable tasks: For example, a large-scale migration or a review of an entire codebase. Turn it on for the session, then turn it off when you are done.
- You have one large task: Just include the word
ultracodein your prompt in an interactive conversation. - Routine small changes, or a tight usage allowance: Leave it off. Small tasks are not worth the extra tokens.
Penchan’s Take
These two articles were made by Penchan asking his AI team to use workflow and ultracode. The research step alone had 4 agents running for about 12 minutes, and they spotted the change in late September along the way.
ultracode hands Claude the decision about when a task is worth bringing in a group of agents; you still decide which sessions to turn it on for and how much of your budget to spend. Penchan’s approach is to turn it on when needed and turn it off when done. If you want to try it, start with one clearly scoped task. Run it once with the keyword and see how much time and usage it takes.
Further Reading
- What Are Claude Code Dynamic Workflows?
- How to Choose Claude Code Effort
- Claude Opus 4.8: Release Overview
- What Is a Multi-Agent Harness?
- Claude Code Beginner’s Guide
References
- Claude Code Docs, Dynamic workflows: https://code.claude.com/docs/en/workflows
- Claude Code Docs, Model configuration: https://code.claude.com/docs/en/model-config
- Claude Code Docs, Settings: https://code.claude.com/docs/en/settings
- Claude Code Docs, Ultrareview: https://code.claude.com/docs/en/ultrareview
- Claude Code CHANGELOG: https://raw.githubusercontent.com/anthropics/claude-code/main/CHANGELOG.md
- Anthropic, Introducing dynamic workflows in Claude Code: https://claude.com/blog/introducing-dynamic-workflows-in-claude-code
This article provides consumer information about AI product features and subscription plans. It does not provide securities or investment advice. Actual features, usage limits, and pricing are subject to Anthropic’s latest announcements. The information in this article is as of October 3, 2026, and may be outdated.