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Cmd. /code-reviewCmd. /runCmd. /run-skill-generatorCmd. /security-reviewCmd. /simplifyCmd. /verify

Models and settings

Cmd. /claude-apiCmd. /configCmd. /effortCmd. /fastCmd. /modelCmd. /output-styleCmd. /update-config

Permissions and integrations

Cmd. /agentsCmd. /hooksCmd. /ideCmd. /mcpCmd. /permissionsCmd. /pluginCmd. /reload-pluginsCmd. /reload-skillsCmd. /sandboxCmd. /skillsCmd. /web-setup

Status and diagnostics

Cmd. /debugCmd. /diffCmd. /doctorCmd. /fewer-permission-promptsCmd. /release-notesCmd. /team-onboarding

Display and input

Cmd. /colorCmd. /focusCmd. /keybindingsCmd. /powerupCmd. /statuslineCmd. /terminal-setupCmd. /themeCmd. /tui

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Cmd. /upgradeCmd. /usageCmd. /usage-credits

Legacy

Cmd. /costCmd. /pr-commentsCmd. /reviewCmd. /statsCmd. /ultrareviewCmd. /vimCmd. /approved-toolsCmd. /commandsCmd. /extra-usageCmd. /settingsCmd. /tagCmd. /todos

Verification and history

Current verification scopeHandbook updatesRelease coverage historyEarlier verification recordsCommand change history
Handbook›Claude Code Command Master›Cmd. /fast
한국어KOEnglishEN

Cmd. /fast

Switches the supported model's fast processing path. It is separate from reasoning effort and may have different billing or quota rules.

Written and reviewed by Eric Han · Co-founder & CTO, reopt

Key takeaways

  • Toggle fast mode.
  • Check the input surface and availability before using the examples below.

Purpose

Toggle fast mode.

/fast [on|off]

Availability

FieldValue
Input surfaceRunning CLI prompt
KindBuilt-in
StatusCurrent reference
Aliases—
Documented minimumNot specified
Reviewed against2026-10-23 · Claude Code 2.1.308

Supported on Opus 5.5, Opus 5, and Opus 4.8; Opus 5.5 is the default from v2.1.280. Account or organization settings can disable it.

Examples

/fast

Effects and persistence

Switches the supported model's fast processing path. It is separate from reasoning effort and may have different billing or quota rules.

Supported models and pricing

Fast mode runs the same Opus model with a speed-prioritized API configuration. It is supported on Opus 5.5, Opus 5, and Opus 4.8; Opus 5.5 is the default from Claude Code v2.1.280 (Opus 5 on v2.1.219–v2.1.279). It is available on the Anthropic API and subscription plans (billed from usage credits), not on Bedrock, Google Cloud Agent Platform, Microsoft Foundry, or Claude Platform on AWS.

ModelInput (MTok)Output (MTok)
Opus 5.5$8$40
Opus 5$10$50
Opus 4.8$10$50

Turning it on mid-conversation charges the whole context once at the uncached fast-mode input rate.

Remote sessions

Cloud and self-hosted-runner Remote sessions honor the host fast-mode setting or /fast where organization policy permits.

Changelog

Cautions

Fast mode has its own availability and pricing. Do not treat it as a lower reasoning-effort setting.

Official sources

  • Commands
  • Fast Mode

Complete command list · Verification scope

Related docs

Cmd. /model

Saves the selected model as the default for new sessions. Press s on a picker row, or use a supported -p invocation, for a session-only change.

Cmd. /effort

Set or inspect model-specific reasoning effort.

Verification Report

Claude Code Complete Guide · Verification checklist for the English Claude Code handbook locale.

Plan and Environment Setup

Claude Code Complete Guide · Prepare Claude Code plans, installation, update policy, and a safe repository baseline.

Update Log

Claude Code Complete Guide · English edition changes for the Claude Code Complete Guide.

Cmd. /effort

Set or inspect model-specific reasoning effort.

Cmd. /model

Saves the selected model as the default for new sessions. Press s on a picker row, or use a supported -p invocation, for a session-only change.

On this page

PurposeAvailabilityExamplesEffects and persistenceSupported models and pricingRemote sessionsCautionsOfficial sources