Claude Fable 5.2 vs Opus 5.5: Is Double the Price Worth It? (November 2026)

	Claude Fable 5.2	Claude Opus 5.5
Released	November 9, 2026	September 22, 2026
Input per 1M tokens	$8	$4
Output per 1M tokens	$40	$20
Cached input read	$0.20	$0.20
Context window	1M	1M
Max output	128K	128K
AA Intelligence Index (max effort)	65	59
Anthropic's positioning	Most demanding long horizon work	Default for everyday coding and knowledge work

Anthropic released Claude Fable 5.2 on November 9, 2026, alongside Claude Mythos 5.2. It costs exactly twice what Claude Opus 5.5 costs, with the same 1M token context window, the same 128K output limit, and the same cache read price. A request with 1M input tokens and 200K output tokens costs $8 on Opus and $16 on Fable. So the whole question is whether the capability gap is worth a doubled bill, and the answer depends heavily on what kind of work you send it.

The launch table: 11 of 12 rows, but read the margins

Benchmark (Anthropic reported)	Fable 5.2	Opus 5.5	Gap
FrontierCode 2.0 (agentic coding)	49.1%	45.5%	3.6
FrontierSWE v2 (agentic coding)	69.9%	62.3%	7.6
AutomationBench (business workflows)	51.4%	42.5%	8.9
Terminal Bench Science 0.1	74.6%	58.7%	15.9
OSWorld 2.1 (computer use)	89.3%	87.2%	2.1
WANDR (agentic search)	82.1%	72.3%	9.8
RoboDojo Sim (robotics)	64.9%	39.4%	25.5
Remote Labor Index (high effort)	41.3%	21.3%	20.0
Humanity's Last Exam (with tools)	74.2%	67.7%	6.5
Chartography (no tools)	73.4%	64.4%	9.0
AA Briefcase v1.1 (rubric)	66.1%	61.2%	4.9
AA Briefcase v1.1 (Elo)	1785	1800	Opus leads

Fable 5.2 wins 11 rows. Counting rows hides the real story, which is how uneven the margins are.

On everyday agentic coding the lead is small. FrontierCode 2.0 separates them by 3.6 points, and that Fable score was run at a higher effort setting. At matched high effort Fable scores 45.3% against 45.5% for Opus, a statistical tie. Computer use on OSWorld 2.1 is 2.1 points apart. Opus keeps the one office work row outright, AA Briefcase Elo.

On long horizon and science heavy work the lead is large. Terminal Bench Science is nearly 16 points. Remote Labor Index, which measures how much real freelance work a model can complete end to end, nearly doubles from 21.3% to 41.3%. RoboDojo is more than 25 points. Anthropic's showcase points the same direction: about 1,000 Fable 5.2 agents formalized Fermat's Last Theorem in Lean in roughly 30 hours, while Opus 5.5 reached about 26% of the way in 18 hours.

The independent data so far agrees. On the Artificial Analysis Intelligence Index, Fable 5.2 at max effort scores 65 against 59 for Opus 5.5.

Cost per task: effort is the real price dial

Anthropic's case for Fable is that a more capable model can do the same job with less effort. Its figures:

1. On FrontierCode at high effort, Fable 5.2 matches Opus 5.5's best score at roughly half the cost per task.
2. On WANDR at medium effort, Fable matches Opus's top score at about 40% of the cost per task.
3. On Humanity's Last Exam at low effort, Fable matches Opus's top score at under a tenth of the cost.

Early third party testing is less tidy. One test found Fable 5.2 costing between 1.7 and 6.5 times as much as Opus for the same job. A developer reported a max effort attempt that spent 128,000 output tokens on thinking and returned no result, about $5.12 for nothing, and another max effort run that used 250,082 output tokens where Fable 5.1 used 99,072.

Both sets of results are consistent once you look at effort level. Artificial Analysis measured Fable 5.2 at:

Effort	Index score	Cost per index task
Medium	56	$3.80
High	62	$9.08
Max	65	$26.54

The last three index points cost nearly three times the previous six. Fable at medium or high effort is a strong and reasonably priced model. Fable at max effort is a specialist tool for problems that justify it. Start at medium, raise effort only when results demand it, and cap output tokens on anything automated.

What changes besides price and scores

Safeguards. Fable 5.2 shares its underlying model with Mythos 5.2 and adds classifiers that block penetration testing, exploit generation, and most research level biology. Anthropic says it produces fewer unnecessary blocks than Fable 5.1. Mythos 5.2, without those safeguards, is limited to vetted organizations. Anthropic also says it limited Fable's AI research and development capability to roughly the level of Opus 5.5. If your work brushes against security research, test for false positives before migrating, or stay on Opus.

Data retention. Fable 5.2 requires 30 day retention for safety monitoring unless your organization has a separate enterprise arrangement. Teams with zero retention requirements need to check this before anything else.

Integration details. Fable 5.2 enforces a prefix check: editing the system prompt, tools, or earlier turns and then replaying a later thinking block returns an error. The older computer use tool version is rejected in favor of the current toolset. Switching to Fable mid conversation keeps Opus reasoning blocks, but switching away drops Fable's.

Fast mode. Fable 5.2 offers a fast mode at $16 input and $80 output for up to 2.5 times the output speed.

How to route between them

Workload	Use	Why
Well scoped coding tasks, routine agent loops	Opus 5.5	Tie at matched effort, half the price
Office and document work	Opus 5.5	Leads AA Briefcase Elo
Multi hour autonomous tasks	Fable 5.2	Remote Labor Index nearly doubles
Scientific computing and research	Fable 5.2	16 point lead on Terminal Bench Science
Agentic search and deep research	Fable 5.2 at medium effort	Matches Opus's best at about 40% of the cost
Robotics and embodied planning	Fable 5.2	Largest gap in the table
Security adjacent work	Opus 5.5, or test Fable carefully	Fable's classifiers block more

Anthropic's own guidance is the right default: Opus 5.5 for everyday work, Fable 5.2 for the hardest long horizon tasks. If you are weighing Fable against OpenAI's premium tier instead, see Fable 5.2 vs GPT 6 Astra. If you are looking for something cheaper than Opus, see Grok 4.7 vs Opus 5.5 and Sonnet 5.5 vs Opus 5.5.

FAQ

How much more does Fable 5.2 cost than Opus 5.5? Exactly double on input and output: $8 and $40 per million tokens against $4 and $20. Cache reads are the same at $0.20.

Is Fable 5.2 better at coding than Opus 5.5? Slightly, on Anthropic's numbers: 3.6 points on FrontierCode 2.0 and 7.6 on FrontierSWE v2. At matched high effort the FrontierCode result is a tie. For most coding work Opus 5.5 is the better value.

Where is Fable 5.2 clearly ahead? Long horizon autonomous work, scientific tasks, agentic search, and robotics simulation, with gaps of 10 to 25 points.

Do Fable 5.2 and Opus 5.5 have the same context window? Yes. Both have a 1M token context window and a 128K output limit.

Which effort level should we start with on Fable 5.2? Medium. Max effort costs roughly seven times as much per task as medium in independent runs and is only worth it for the hardest problems.

When this applies to your stack

The useful question is not which Claude model is better. It is which of your requests are hard enough to deserve the expensive one. Most teams will find that a small share of long, difficult tasks benefit from Fable 5.2 and the rest run better and cheaper on Opus 5.5. Finding that split requires running your own tasks through both at pinned effort levels and measuring cost per completed task. Building that evaluation harness and the routing layer behind it is the kind of applied AI work we do at Contra Collective.