# Claude Fable 5.2 vs Opus 5.5: which to use for coding Authors: AutoRouter Author profile: https://autorouter.com/about Published: 2026-11-09T17:50:00.000Z Updated: 2026-11-10T17:50:00.000Z Reading time: 10 min Canonical: https://autorouter.com/blog/claude-fable-5-2-vs-opus-5-5 Publisher: AutoRouter, the Mac app that routes Codex, Claude Code and other AI tools to every model (https://autorouter.com) About AutoRouter: a Mac app (macOS 14 or later) that adds every leading model to Codex, Claude Code, Claude Desktop, T3 and Terminal and picks the model for each task, using your ChatGPT and Claude plans first. Install from https://autorouter.com/AutoRouter.dmg, or ask your agent to follow https://autorouter.com/setup.md. Routing across your plans is free; Pro is $50 a month with $20 of included usage. Unrelated to OpenRouter's Auto Router. > Keep everyday coding on Claude Opus 5.5 and move to Claude Fable 5.2, released November 9, 2026, for major refactors, migrations, long unattended runs and tasks where Opus 5.5 at high effort still falls short. As of November 10, 2026, Fable 5.2 costs $8 per million input tokens and $40 per million output tokens, twice Opus 5.5's price, with the same $0.20 cache-read price. By the arithmetic of AutoRouter, the Mac app for Codex and Claude Code, one assumed agent request costs $0.139 on Fable 5.2 and $0.074 on Opus 5.5. ## Key facts - As of November 10, 2026, Claude Fable 5.2 costs $8 per million input tokens and $40 per million output tokens, twice Claude Opus 5.5's $4 and $20, and both charge $0.20 per million tokens for cache reads ([Anthropic](https://platform.claude.com/docs/en/about-claude/pricing)). - One assumed agent request (45,000 cached input tokens, 5,000 new input tokens and 2,000 output tokens) costs $0.139 on Claude Fable 5.2 and $0.074 on Claude Opus 5.5 at list prices on November 10, 2026, by AutoRouter's arithmetic. - Anthropic's November 9, 2026 guide starts most work on Claude Opus 5.5 at medium effort and moves up to Claude Fable 5.2 for major refactors, migrations, long unattended runs, and work where Opus 5.5 at high effort still falls short ([Anthropic](https://claude.dev/blog/which-claude-model-should-you-build-with/)). - Anthropic reports that on FrontierCode 2.0, Claude Fable 5.2 at high effort scored 45.3% against 45.5% for Claude Opus 5.5 at max effort, for roughly half the cost per task ([Anthropic](https://www.anthropic.com/claude-fable-and-mythos-5-2), November 9, 2026). - As of November 10, 2026, Claude Max and Ultra include Fable models for up to 50% of weekly usage limits, and on Claude Pro they run on usage credits after a launch week that ends November 16, 2026 ([Anthropic](https://support.claude.com/en/articles/15424964-claude-fable-models-on-your-plan)). As of November 10, 2026, keep everyday coding on Claude Opus 5.5, and move a task to Claude Fable 5.2 when it is a major refactor, a migration, a long unattended run, or work where Opus 5.5 at high effort still falls short. That is [Anthropic's own advice](https://claude.dev/blog/which-claude-model-should-you-build-with/), published with Fable 5.2 on November 9, 2026. Fable 5.2 costs [$8 per million input tokens and $40 per million output tokens](https://platform.claude.com/docs/en/about-claude/pricing), twice Opus 5.5's $4 and $20, and both charge $0.20 per million tokens for cache reads. [AutoRouter](https://autorouter.com), the Mac app for Codex and Claude Code, wrote this post and worked the prices through: one assumed agent request costs $0.139 on Fable 5.2 and $0.074 on Opus 5.5. ![AutoRouter's launch poster for Claude Fable 5.2. It reads: On Monday, Nov 9, Anthropic released Claude Fable 5.2. Frontier model for the most ambitious, open-ended technical work. Now in AutoRouter. Fable 5.2. The picture is a porch held up by carved figures, drawn in white tokenizer tokens on a blue ground.](https://autorouter.com/models/claude-fable-5-2.png) ## When is Claude Fable 5.2 worth using over Opus 5.5? Claude Fable 5.2 is worth its price on the hardest and longest technical work, and Claude Opus 5.5 is the better choice for most daily coding. Anthropic's [models overview](https://platform.claude.com/docs/en/models/overview) describes Fable 5.2 as the model for "demanding reasoning and long-horizon agentic work" and says to start most workloads on Opus 5.5. Its [guide to choosing a model](https://claude.dev/blog/which-claude-model-should-you-build-with/) says to adjust effort before changing models: raise Opus 5.5 from `medium`, Claude Code's default effort for both models, to `high`, and once you would go past `high`, test Fable 5.2 at a lower effort instead. | Kind of work | Start with | Why (Anthropic's guide, November 9, 2026) | | ----------------------------------------------------------------------------- | ------------------------------------------------------ | --------------------------------------------------------------------------------------- | | Everyday engineering, debugging and feature work across several pull requests | Opus 5.5 at `medium`, then `high` | The guide starts this work on Opus 5.5, at half Fable 5.2's price per token. | | Major refactors, migrations and architecture planning | Fable 5.2 at `medium`, then `high` | The guide lists all three under Fable 5.2, with leading many subagents. | | Long unattended runs | Fable 5.2 | The guide says to move up for them. | | A hard task where Opus 5.5 at `high` still falls short | Fable 5.2, at a lower effort than you used on Opus 5.5 | The guide warns that an effort level above `high` can cost as much as the bigger model. | | Computer use and work heavy on screenshots | Opus 5.5 at `medium` | The guide describes these long agentic loops as work Opus 5.5 is built for. | | You aren't sure yet | Opus 5.5 at `medium` | It is Claude Code's default model on every plan and on the Anthropic API. | Test each row on your own repository. [Which model to use for which coding task](/blog/which-model-for-which-task) covers the models below Opus 5.5 and OpenAI's lineup. ## How much does Claude Fable 5.2 cost compared with Opus 5.5? Claude Fable 5.2 costs twice as much as Claude Opus 5.5 for input, cache writes and output, and the same for cache reads, as of November 10, 2026 ([pricing](https://platform.claude.com/docs/en/about-claude/pricing)). Both models bill their full 1M-token context window at one rate. | List price, November 10, 2026 | Claude Fable 5.2 | Claude Opus 5.5 | | -------------------------------------------- | ---------------- | --------------- | | Input, per million tokens | $8 | $4 | | 5-minute cache write, per million tokens | $10 | $5 | | 1-hour cache write, per million tokens | $16 | $8 | | Cache read, per million tokens | $0.20 | $0.20 | | Output, per million tokens | $40 | $20 | | Fast mode, input / output per million tokens | $16 / $80 | $8 / $40 | | Default effort on the API | `high` | `medium` | | Default effort in Claude Code | `medium` | `medium` | A coding agent sends the whole conversation with each request and reads most of it from the cache, so one request costs a little under twice as much on Fable 5.2. The example prices the assumed request AutoRouter's posts use: 45,000 cached input tokens, 5,000 new input tokens written to the 5-minute cache Claude Code [uses with an API key](https://code.claude.com/docs/en/prompt-caching#which-ttl-each-request-gets), and 2,000 output tokens, thinking included. ```text One assumed agent request, list prices as of November 10, 2026 Claude Fable 5.2 45,000 cached input x $0.20 per million = $0.009 5,000 new input x $10.00 per million = $0.050 (5-minute cache write) 2,000 output x $40.00 per million = $0.080 Total $0.139 Claude Opus 5.5 45,000 cached input x $0.20 per million = $0.009 5,000 new input x $5.00 per million = $0.025 (5-minute cache write) 2,000 output x $20.00 per million = $0.040 Total $0.074 ``` The Fable 5.2 request costs 1.9 times as much, a difference of $0.065. At this request size, $20 of API usage pays for 143 requests on Fable 5.2 or 270 on Opus 5.5. The cached part costs the same on both models, so a session that mostly re-reads its context narrows the ratio, and a task that writes a lot of code moves it toward 2 times. ## What does a finished task cost on each model? A finished task can cost less on Claude Fable 5.2 when it is hard enough that Claude Opus 5.5 needs its highest effort, and it costs close to twice as much, for the same tokens, when Opus 5.5 would have finished it at `medium`. Two results published by November 10, 2026 show the first case: - **Anthropic's test.** On FrontierCode 2.0, which checks whether the maintainers of open-source repositories would merge a model's changes, Anthropic [reports](https://www.anthropic.com/claude-fable-and-mythos-5-2) that Fable 5.2 at `high` effort scored 45.3% against 45.5% for Opus 5.5 at `max`, for roughly half the cost per task. At `xhigh`, Fable 5.2 scored 49.1%. - **An outside test.** Vals AI, an independent evaluator, ran [Fable 5.2 at `high` effort](https://www.vals.ai/models/anthropic_claude-fable-5-2) and scored it 71.31% on its Vals Index at $17.94 per test. Its page for [Opus 5.5](https://www.vals.ai/models/anthropic_claude-opus-5-5) lists `max` effort, 70.14% and $24.77 per test. Each score carries a margin of about one point, so the two overlap. The first result is Anthropic's own, and the Vals Index mixes coding benchmarks with others such as a finance agent test. To price your own work, run one hard task from your backlog on both models and compare what `/usage` shows. On everyday tasks, AutoRouter has measured Opus 5.5 and has not yet measured Fable 5.2. In [What common Claude Code tasks cost, measured on each model](/blog/claude-code-task-costs-measured), five small tasks in a 1,176-line Python library averaged $0.110 per run on Opus 5.5 as Claude Code priced them on a Max plan on October 28, 2026, and all 15 runs passed their checks. Small, well-specified tasks like these already pass on Opus 5.5, so they are work to keep there. The study did not test migrations or long unattended runs, the work Anthropic's guide gives to Fable 5.2. ## How does Fable 5.2 count against a Claude plan? On Claude Max and Ultra, Fable models are included for up to 50% of your weekly usage limits, and on Claude Pro they run on usage credits billed on top of the plan, as of November 10, 2026 ([Anthropic](https://support.claude.com/en/articles/15424964-claude-fable-models-on-your-plan)). Opus 5.5 is Claude Code's [default model](https://code.claude.com/docs/en/model-config#default-model-setting) on every plan. - **Max ([$100 a month](https://claude.com/pricing)) and Ultra ($200).** Fable usage draws from the same weekly limit as every other model and uses it faster; Anthropic doesn't publish how much faster. Once half the weekly limit has gone to Fable models, you continue on usage credits or switch to another model. - **Pro ($20 a month).** Fable models aren't part of the plan's limits. Each request bills to usage credits at [standard API rates](https://support.claude.com/en/articles/12429409-manage-usage-credits-for-paid-claude-plans), so the per-request math above applies. With `claude -p`, Claude Code [bills Fable requests to usage credits without asking](https://code.claude.com/docs/en/model-config#fable-and-usage-credits). - **Launch week.** Through November 16, 2026, Pro includes Fable models for up to 50% of weekly limits, and Max and Ultra subscribers get one to three Fable limit resets ([launch offers](https://support.claude.com/en/articles/17506494-claude-fable-5-2-launch-offers)). After that week, Pro goes back to usage credits. [Claude Code pricing explained, with what a real task costs](/blog/claude-code-pricing) covers every plan's price and limits. ## What breaks when you switch models mid-conversation? Two things change when you switch between Claude Fable 5.2 and Claude Opus 5.5 mid-conversation, as of November 10, 2026: the new model has no prompt cache for the conversation, and a move down from Fable 5.2 loses its reasoning. - **The cache starts over.** Each model has its own prompt cache, so the first request after a switch [reads the whole conversation with no cache hits](https://code.claude.com/docs/en/prompt-caching#switching-models) and pays the cache-write price on all of it. With an API key and 100,000 tokens of conversation, that request costs $1.00 in cache writes on Fable 5.2 or $0.50 on Opus 5.5. Reading the same tokens from a warm cache on the model you were already using costs $0.02. - **Reasoning carries upward only.** On the Claude API, Fable 5.2 reads the thinking blocks Opus 5.5 produced, so a move up [keeps the conversation's reasoning](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5). Opus 5.5 can't read Fable 5.2's blocks: after a move down, the API drops them, the request still succeeds, and Opus 5.5 works without that reasoning ([What's new in Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2)). Anthropic's guide says to switch at a natural break: run `/compact` first in Claude Code, or start a new session with a short written plan, so the first request on the new model is small. On the API, Fable 5.2 also answers with a [400 error](https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2) on every account when a request changes anything that came before one of its thinking blocks. Anthropic says nothing changes when Claude Code builds your requests. ## How does AutoRouter choose between Fable 5.2 and Opus 5.5? AutoRouter, the Mac app for Codex and Claude Code, [picks a model for each task](https://autorouter.com/#product) while it is the model selected. Your rules go first. Otherwise AutoRouter works out how hard the task is and only considers models that clear the quality bar for it. Hard work goes to the most capable model your plans cover, and to credits only when none is strong enough. Everything else goes to the model that costs you least. A task that continues keeps its model or moves up. In Claude Code, Claude models run on your Claude plan. New models show up in the picker right away. You can choose Fable 5.2 or Opus 5.5 there yourself, which sends every request straight to that model, or write a rule in plain English. [AutoRouter's guide](https://autorouter.com/llms.txt) gives "Never use Fable for any tasks." as an example, and an avoid rule is always respected. Every request shows its model, what it cost and why. AutoRouter is in beta and sometimes misjudges how hard a task is; you can rate the pick. It earns 10% on paid models and nothing on your plans. ## Questions ### Is Claude Fable 5.2 better than Opus 5.5 at coding? On Anthropic's hardest coding benchmarks, yes. In its [November 9, 2026 announcement](https://www.anthropic.com/claude-fable-and-mythos-5-2), Anthropic reports 49.1% for Fable 5.2 at `xhigh` effort against 45.5% for Opus 5.5 at `max` on FrontierCode 2.0, and 69.9% against 62.3% on FrontierSWE v2. Vals AI, which ran Fable 5.2 at `high` and lists Opus 5.5 at `max`, has the two tied on Terminal-Bench 4.0 at 65.15% and Opus 5.5 ahead on SWE-bench Multimodal, 70.21% to 62.29%, as of November 10, 2026. For everyday coding, Anthropic recommends starting on Opus 5.5. ### Should you raise effort on Opus 5.5 or switch to Fable 5.2? Raise effort first, up to `high`. Anthropic's [guide](https://claude.dev/blog/which-claude-model-should-you-build-with/) gives the order: check that the model can verify its own work with a test or a build, raise effort one level, then move to the next model up at a lower effort than you used on the smaller one. It adds that more effort doesn't give a model knowledge or skill it lacks. ### How do you select Fable 5.2 in Claude Code? Run `/model fable` in a session, or start one with `claude --model fable`. The `fable` alias points to Fable 5.2 from Claude Code v2.1.321, so run `claude update` first on an older version ([model configuration](https://code.claude.com/docs/en/model-config#work-with-fable)). Fable 5.2 starts at `medium` effort until you change it with `/effort`. [How to change the model in Claude Code](/blog/claude-code-model-settings) covers every setting. ### How much cheaper is Fable 5.2 than Fable 5.1? Fable 5.2 is 20% cheaper per token: $8 and $40 per million input and output tokens against $10 and $50 for Fable 5.1, with cache reads at $0.20 against $0.25, as of November 10, 2026 ([pricing](https://platform.claude.com/docs/en/about-claude/pricing)). Anthropic also says Fable 5.2 generates output up to 30% faster than Fable 5.1. ## Sources - [Pricing](https://platform.claude.com/docs/en/about-claude/pricing), Claude Platform docs, Anthropic, checked November 10, 2026 - [Which Claude model should you build with?](https://claude.dev/blog/which-claude-model-should-you-build-with/), Anthropic, November 9, 2026 - [Introducing Claude Fable 5.2 and Claude Mythos 5.2](https://www.anthropic.com/claude-fable-and-mythos-5-2), Anthropic, November 9, 2026 - [Models overview](https://platform.claude.com/docs/en/models/overview), Claude Platform docs, Anthropic - [What's new in Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2), Claude Platform docs, Anthropic - [What's new in Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5), Claude Platform docs, Anthropic - [Model configuration](https://code.claude.com/docs/en/model-config), Claude Code docs, Anthropic - [How Claude Code uses prompt caching](https://code.claude.com/docs/en/prompt-caching), Claude Code docs, Anthropic - [Plans and pricing](https://claude.com/pricing), Anthropic, checked November 10, 2026 - [Claude Fable models on your plan](https://support.claude.com/en/articles/15424964-claude-fable-models-on-your-plan), Claude Help Center - [Claude Fable 5.2 launch offers](https://support.claude.com/en/articles/17506494-claude-fable-5-2-launch-offers), Claude Help Center - [Manage usage credits for paid Claude plans](https://support.claude.com/en/articles/12429409-manage-usage-credits-for-paid-claude-plans), Claude Help Center - [Claude Fable 5.2](https://www.vals.ai/models/anthropic_claude-fable-5-2) and [Claude Opus 5.5](https://www.vals.ai/models/anthropic_claude-opus-5-5), Vals AI, checked November 10, 2026 ## Read next - [Claude Opus 5.5 vs Sonnet 5.5: which to use for coding](https://autorouter.com/blog/claude-opus-5-5-vs-sonnet-5-5.md): Start coding work on Claude Opus 5.5, released September 22, 2026 and Claude Code's default model, interface design and animation included, and move a task down to Claude Sonnet 5.5 when it is well scoped, such as a bug fix or a feature built against a spec. As of November 10, 2026, Opus 5.5 costs $4 per million input tokens and $20 per million output tokens, twice Sonnet 5.5's $2 and $10. By the arithmetic of AutoRouter, the Mac app for Codex and Claude Code, one assumed agent request costs $0.074 on Opus 5.5 and $0.037 on Sonnet 5.5. - [Gemini 4 Carbon vs Gemini 4 Argon: which to use for coding](https://autorouter.com/blog/gemini-4-carbon-vs-argon.md): Keep everyday coding on Gemini 4 Argon, and bring in Gemini 4 Carbon, generally available since November 10, 2026, for root-cause debugging in large codebases, architecture changes, migrations and security audits. As of November 10, 2026, the two models share one price list: $2 per million input tokens and $10 per million output tokens through November 30, then $4 and $20, and Google says Carbon uses more tokens on each request. By the arithmetic of AutoRouter, the Mac app for Codex and Claude Code, one assumed agent request costs $0.0345 on either model now and $0.069 from December 1. - [Muse Ember vs Claude Haiku 5.5: Meta's low-cost model for coding](https://autorouter.com/blog/muse-ember-vs-claude-haiku-5-5.md): Muse Ember is Meta's smallest Muse model, released on November 9, 2026 at $0.10 per million input tokens and $0.50 per million output tokens, the same list prices as Claude Haiku 5.5 and GPT-6 Luna on prompts up to 100,000 tokens. Meta says it matches Haiku 5.5's best score on the Artificial Analysis Intelligence Index at about a third of the cost per task, and Meta's own docs keep multi-file changes on a larger model. AutoRouter, the Mac app for Codex and Claude Code, has Muse Ember in its model picker. Tags: [Models](https://autorouter.com/blog/tags/models.md), [Claude Code](https://autorouter.com/blog/tags/claude-code.md), [Comparisons](https://autorouter.com/blog/tags/comparisons.md) Drafted with AI from the sources linked above, then checked and edited by the AutoRouter team.