Cmd. /model

Purpose

Select a model and save the default.

/model [model]

Availability

Without arguments, opens a picker. In -p on v2.1.205+, supply a model; the change is session-only.

Examples

/model

Effects and persistence

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.

Choosing scope

Open /model to use the picker. A normal selection is saved as a default for new sessions; press s on a row for the current session only. Provider aliases can resolve to different model versions, so use a full model ID for reproducible comparisons.

Fable 5.1 Baseline

Claude Fable 5.1 (claude-fable-5-1) was released on 2026-09-01 and is the default Fable model from Claude Code v2.1.257 (the model-config docs list v2.1.255 as the minimum). It is not the default model on any plan or provider; select it with /model fable, claude --model fable, the model setting, or best where the organization has access. Fable 5 remains available as a legacy model via /model claude-fable-5, and the availableModels prefix claude-fable-5 permits both.

Claude Code keeps conversation history append-only, so the history-editing rule does not affect interactive sessions. Custom harnesses can start with /claude-api migrate this project to claude-fable-5-1.

Fable Plan Access

The temporary subscription allowance ended on 2026-07-07. As of 2026-07-19, keep seat-based subscription usage separate from API consumption. The Fable 5.1 announcement did not change plan inclusion, so treat these Fable 5 rules as the Fable-family baseline until a plan-specific notice lands:

Usage credits are billed separately from the subscription at standard API rates. Configure payment, prepaid balance, monthly caps, and auto-reload in Settings > Usage; use /usage-credits from Claude Code to open the corresponding account flow. Teams should set an admin policy and spending cap before making Fable the default path.

Fable Refusal and Fallback

A Fable safety-classifier refusal is a successful HTTP 200 Messages API response on both Fable 5.1 and Fable 5. Branch on stop_reason, not on HTTP errors, empty content, or stop_details:

{
  "model": "claude-fable-5-1",
  "content": [],
  "stop_reason": "refusal",
  "stop_details": {
    "type": "refusal",
    "category": "cyber",
    "explanation": "..."
  }
}

stop_details.category may identify an area such as cyber or bio, but it can be null and the human-readable explanation is not a stable parsing contract.

• Do not combine server-side fallbacks and the SDK refusal-fallback middleware on one request.
• Message Batches can return refused items as result.type: "succeeded"; inspect stop_reason. Server-side fallbacks is not supported for batches.
• Claude Code fallbackModel and --fallback-model handle availability failures. They are not the same setting as the Messages API refusal fallback.
• A request refused before output is not billed. Server-side fallback and the SDK middleware apply fallback credit automatically; manual retry logic must redeem the credit token to avoid paying the prompt-cache write cost twice when switching models.
• Instrument refusals and fallback-served responses separately. HTTP-error monitoring alone cannot reveal this path.

Prompts, skills, and harness instructions that ask Fable to echo, transcribe, or expose its internal reasoning can trigger the reasoning_extraction refusal category and increase fallback to Opus 4.8. Ask for a concise rationale, verification evidence, and user-facing progress instead. When an API integration needs reasoning visibility, consume the structured adaptive-thinking blocks.

Official Fable References

• Claude Fable 5.1 overview: https://platform.claude.com/docs/en/models/fable-5-1/overview
• What's new in Claude Fable 5.1: https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1
• Migrating to Claude Fable 5.1: https://platform.claude.com/docs/en/models/fable-5-1/migration-guide
• Prompting Claude Fable 5.1: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1
• Fable 5.1 and Mythos 5.1 announcement: https://www.anthropic.com/claude-fable-and-mythos-5-1
• Fable 5 introduction and API differences: https://platform.claude.com/docs/en/models/fable-5/introducing-claude-fable-5-and-claude-mythos-5
• Refusals and fallback: https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback
• Fallback credit: https://platform.claude.com/docs/en/build-with-claude/fallback-credit
• Prompting Claude Fable 5: https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5
• Usage credits: https://support.claude.com/en/articles/12429409-manage-usage-credits-for-paid-claude-plans

Cautions

Switching with existing conversation history may require a full uncached reread. Check the selected model and provider after switching.

Official sources

• Commands
• Model Config
• Changelog
• Overview
• Whats New Fable 5 1
• Migration Guide
• Prompting Claude Fable 5 1
• Claude Fable And Mythos 5 1
• Introducing Claude Fable 5 And Claude Mythos 5
• Redeploying Fable 5
• Refusals And Fallback
• Fallback Credit
• Prompting Claude Fable 5
• 12429409 Manage Usage Credits For Paid Claude Plans
• Overview
• Claude Sonnet 5

Complete command list · Verification scope