Claude Code 2.1.321, published on GitHub on 9 November 2026, makes Claude Fable 5.2 (claude-fable-5-2) the default Fable model, priced at $8 per million input tokens and $40 per million output tokens with a 1M-token context window (release notes). Fable 5.1 cost $10 and $50 for the same units (Classmethod), so the new model is 20% cheaper on input, output and cache reads. The verdict: if you already use Fable in Claude Code, 5.2 wins over 5.1 on price, speed and Anthropic's published benchmarks, and the upgrade is close to automatic. Anthropic's own guidance still points to Opus 5.5 as the daily driver for most coding work.
TL;DR
- Claude Code 2.1.321 adds Fable 5.2 and makes it the default Fable model; saved Fable 5.1 picks move to the
fablealias. - Unit prices fall from $10/$50/$0.25 to $8/$40/$0.20 per million tokens (input, output, cache reads), a 20% cut across the board (release notes; Classmethod).
- Anthropic says Fable 5.2 generates output up to 30% faster than Fable 5.1 (Anthropic).
- The release also fixes four sandbox, permission and secret-handling bugs that matter if you run agents unattended.
- You can revert with
/model claude-fable-5-1. Mythos 5.2 is a separate, restricted variant and is not needed for normal development.
What changed in Claude Code 2.1.321?
The headline item is the model swap. The release notes describe Fable 5.2 as the new default Fable model, with 1M context and cache reads at $0.20 per million tokens. Anthropic's platform documentation lists a 128K maximum output, always-on adaptive thinking and a June 2026 knowledge cutoff (model overview).
Migration is automatic in most cases. Saved Fable 5.1 selections move to the fable alias immediately on Pro and Max plans. On Team and Enterprise plans the move happens once your organisation allows the new model, so an admin setting may delay it.
The release also adds a --settings <file> option to claude remote-control, which applies one settings file to every session that command starts. That is useful if you manage permission rules centrally.
How does Fable 5.2 compare with Fable 5.1 and Opus 5.5?
The figures below come from Anthropic's launch announcement and release notes. Benchmark scores are Anthropic's own, run at the effort levels it chose, so treat them as vendor claims rather than independent results.
| Fable 5.2 | Fable 5.1 | Opus 5.5 | |
|---|---|---|---|
| Input / output per Mtok | $8 / $40 | $10 / $50 | Not stated in the release material |
| Cache reads per Mtok | $0.20 | $0.25 | Not stated |
| FrontierCode 2.0 (Xhigh) | 49.1% | 32.4% | 45.5% |
| FrontierSWE v2 | 69.9% | 56.3% | 62.3% |
| OSWorld 2.1 (offline set, partial) | 89.3% | 83.5% | 87.2% |
| Remote Labor Index | 41.3% (High effort) | 17.9% | 21.3% |
Sources: Anthropic announcement for benchmarks and Fable 5.2 pricing; Classmethod for Fable 5.1 pricing.
Two readings are worth making. First, the gap over Fable 5.1 is large on agentic coding: 49.1% against 32.4% on FrontierCode 2.0. Second, Opus 5.5 is close behind on coding tasks. Anthropic's accuracy-versus-cost data shows Fable 5.2 at High effort scoring about level with Opus 5.5's best FrontierCode 2.0 result (45.3% against 45.5% (Anthropic announcement)) for roughly half the cost per task. If you pay per token, that cost-per-task point matters more than the headline score. For a wider look at how model pricing is shifting, see our Claude Sonnet price comparison against GLM 5.3.
How much does the 20% price cut save in practice?
The saving is simple arithmetic on the published rates, so no benchmark hype is needed. Take an illustrative session that reads 2 million input tokens and writes 200,000 output tokens (figures chosen for easy arithmetic, not measured):
- Fable 5.1: 2 x $10 + 0.2 x $50 = $30.00 (Classmethod rate card)
- Fable 5.2: 2 x $8 + 0.2 x $40 = $24.00 (release notes)
That is $6 saved per session, or 20%. Real sessions vary, because cache reads, thinking tokens and tool output all change the mix, but the ratio holds as long as the token mix is the same. A faster model may also finish sooner, though you should measure that on your own repositories before counting on it.
If you want a larger reduction, the savings from structural changes can exceed a price cut. Our piece on cheaper subagent status updates in Claude Code covers one such approach.
How do I check and switch models after updating?
Follow these steps:
- Update Claude Code to version 2.1.321 or later using your usual install method.
- Run
claude --versionand confirm it reports 2.1.321 or higher. - Start a session and run
/modelto see which model is active. On Pro and Max plans a previous Fable 5.1 choice should now show thefablealias. - To go back to the older model, run
/model claude-fable-5-1. - Run
/fastto check whether fast mode is on. Anthropic lists fast mode at up to 2.5x faster token generation, at $16 per million input tokens and $80 per million output tokens, which is double the standard rate.
Fast mode is a sensible choice for interactive work where waiting is the cost. For long unattended runs, standard mode is usually the cheaper pick.
Which security fixes in Claude Code 2.1.321 matter for unattended agents?
Four fixes in the release notes affect anyone who lets Claude Code run commands without close supervision:
- MCP OAuth requests no longer send secrets, such as refresh tokens, to a different host when a server redirects them.
- A read-only Bash command that could run outside the sandbox without a permission prompt now prompts correctly.
- Bash permission checks no longer judge a file write from the wrong folder and skip the prompt.
- Deny rules and protected-file prompts now apply to the file that a
cpormvinto a directory actually writes.
The fourth is the easiest to underestimate. A deny rule that protects .env is only useful if copying or moving a file into a directory cannot get around it. These fixes follow a security batch in versions 2.1.317 to 2.1.319 a few days earlier (AI Coding Guide), so updating promptly is the practical response. If your agents handle credentials, our guide to Bitwarden versus 1Password for Claude Code secrets covers how to keep them out of reach.
What are the limitations of this upgrade?
Benchmarks are vendor-reported, and scores at different effort levels are not directly comparable. The Fable 5.2 figure for the Remote Labor Index uses High effort while the coding result uses Xhigh. The cost-per-task claim comes from Anthropic's own charts. No independent test of Fable 5.2 on your codebase exists yet, so run a few representative tasks before changing team-wide defaults.
If you work across editors, the picture differs by tool. Our notes on GitHub Copilot in Xcode 27.3 and Cursor's hosted web apps and cloud agents cover alternatives with their own model and pricing arrangements.
Why we covered this release
Of the 694 AI and developer-tooling keywords we priced for the keyword corpus, 72 cleared a winnable bar and 20 of those carry zero keyword difficulty — meaning no established competitor holds the result set (n=694 corpus, filtered to 72 winnable; measured 2026-11-09). Release-day model comparisons like this one sit in exactly that gap: the pricing and benchmark facts are hours old, and nobody has organised them for buyers yet.
FAQ
Q: Is Fable 5.2 the default model in Claude Code 2.1.321?
A: Yes, it is the default Fable model. Saved Fable 5.1 picks move to the fable alias immediately on Pro and Max plans, and on Team and Enterprise plans once your organisation allows it.
Q: How much cheaper is Fable 5.2 than Fable 5.1?
A: It is 20% cheaper. Fable 5.2 costs $8 input, $40 output and $0.20 cache reads per million tokens, against $10, $50 and $0.25 for Fable 5.1 (release notes; Classmethod).
Q: How do I switch back to Fable 5.1?
A: Run /model claude-fable-5-1 inside Claude Code. You can run /model with no argument to confirm which model is currently active.
Q: Do I need Mythos 5.2 verification to use Fable 5.2?
A: No. Fable 5.2 is available to all users. Mythos 5.2 is the same underlying model with some safeguards removed, and it is restricted to organisations in Anthropic's Life Sciences and Cyber Verification Programs.
Q: Is fast mode worth it for Fable 5.2?
A: It depends on what you are optimising. Fast mode generates tokens up to 2.5x faster at twice the standard price ($16 input, $80 output per million tokens (Anthropic)), so it suits interactive sessions where waiting costs more than tokens, but not long unattended runs.
