# Fable 5.5 vs Gemini 4 vs GPT-6.1: Which Can You Use Today?

> As of October 14, 2026, you can call GPT-6.1 Sol and Gemini 4 Argon, available since October 13. Fable 5.5 is unannounced, and GPT-6.1 Astra was shelved.

- URL: https://blog.laozhang.ai/en/posts/gemini-4-vs-gpt-6-vs-fable-5-2
- Published: 2026-09-20
- Updated: 2026-10-16
- Author: LaoZhang AI Team (https://blog.laozhang.ai/en/about)
- Topic: Model Comparisons
- Tags: Claude Fable 5.5, Gemini 4 Argon, GPT-6.1 Sol, GPT-6.1 Astra, AI model release status

---
**As of October 14, 2026, two of the three models in "Fable 5.5 vs Gemini 4 vs GPT-6.1" are something you can call: GPT-6.1 Sol and Gemini 4 Argon.** Google made Argon generally available on October 13, after about two weeks in which only cyber defenders in its Fairwind Program had it. Anthropic still has not announced Claude Fable 5.5, so it has no official model ID, price or published benchmark. And the "GPT-6.1" that leak posts say Fable 5.5 beats is GPT-6.1 Astra, which OpenAI decided not to release.

So a three-way test is still impossible, but a two-way one isn't. You can run Argon and GPT-6.1 Sol against your own tasks today, next to Claude Opus 5.5, Claude Fable 5.1 or GPT-6 Astra. Fable 5.5 has to wait: the rumored October 6 launch passed without a release, and a `claude-fable-5-5` entry reported in Azure on October 13 has not been confirmed by Microsoft or Anthropic. The checklist near the end shows how to tell when that changes.

## Fable 5.5, Gemini 4 Argon and GPT-6.1 status as of October 14, 2026

| Model | Status | Who can use it | Model ID and price | Source |
|---|---|---|---|---|
| Claude Fable 5.5 | Not announced. A `claude-fable-5-5` entry was reported in Azure on October 13, with no statement from Microsoft or Anthropic | No documented access | None published | [Anthropic newsroom](https://www.anthropic.com/news) and [Claude models overview](https://platform.claude.com/docs/en/models/overview) list no Fable 5.5 |
| Gemini 4 Argon | Generally available since October 13 (announced September 30) | Gemini API paid tier and AI Studio; Gemini app and AI Mode for Google AI Pro and Ultra subscribers. Not on the API free tier | `gemini-4-argon`; $2 input / $10 output per million tokens through November 30, then $4 / $20 | [Google's Gemini 4 Argon launch post](https://blog.google/innovation-and-ai/models-and-research/gemini-models/introducing-gemini-4-argon/) and [Gemini API pricing page](https://ai.google.dev/gemini-api/docs/pricing) |
| GPT-6.1 Sol | Released September 29 | OpenAI API; ChatGPT Work and Codex on Plus, Pro, Business, Enterprise and Edu | `gpt-6.1-sol`; $2 / $10 per million tokens up to 272K input | [GPT-6.1 Sol pricing and access guide](https://blog.laozhang.ai/en/posts/gpt-6-1-sol) |
| GPT-6.1 Astra | Canceled before release; no new date | Nobody | None | Wall Street Journal (September 28) and BBC reports quoting OpenAI |

Three more shipped models sit next to those names. **Claude Fable 5.1** (`claude-fable-5-1`, released September 1) costs $10 input / $50 output per million tokens. **Claude Opus 5.5** (`claude-opus-5-5`, released September 22) costs $4 / $20, and Anthropic says it "performs at the level of Claude Fable 5.1 on most work." **GPT-6 Astra** (`gpt-6-astra`, released in September) costs $10 / $50 up to 272K input. Anthropic's most recent model release is Claude Haiku 5.5, on October 7: its lowest-priced model, from $0.10 / $0.50, not a Fable successor.

## Which GPT-6.1? Sol shipped, Astra was canceled

"GPT-6.1" names two different models, and most confusion around this comparison comes from mixing them up.

**GPT-6.1 Sol** shipped on September 29. It has a 1,050,000-token context window and 128,000 output tokens. Requests up to 272K input tokens cost $2 input, $0.10 cached input and $10 output per million tokens. Above 272K, the whole request bills at $4 / $0.20 / $15. Tool calls need the Responses API. The [GPT-6.1 Sol guide](https://blog.laozhang.ai/en/posts/gpt-6-1-sol) covers where to select it and what breaks when you switch.

**GPT-6.1 Astra** has not shipped and has no release date. The Wall Street Journal reported on September 28 that OpenAI was scrapping its release, and the BBC quoted Saachi Jain, OpenAI's head of safety systems, saying the model "didn't quite meet the bar." It fell short on "staying within scope and authorisation and how it communicates back to the user about the type of work it's done." As of October 14, OpenAI has announced no later Astra release. Don't confuse it with GPT-6 Astra, the agentic model OpenAI released in September, which you can still use. The [GPT-6.1 Sol vs GPT-6 Astra comparison](https://blog.laozhang.ai/en/posts/gpt-6-1-sol-vs-gpt-6-astra-vs-gpt-6-sol) covers when the older Astra is worth its higher price.

The "Fable 5.5 > GPT-6.1" claim refers to the canceled Astra. According to [OrcaRouter's account of the leak chain](https://www.orcarouter.ai/blog/claude-fable-5-5-leak), an X user posted "5.5 > 6.1" on October 2, and a widely shared quote post expanded it: "Fable 5.5 is expected to outperform Astra 6.1." The thread includes no screenshot, benchmark, number or date. So the claim compares an unannounced model with a model that hasn't been released. It tells you nothing about GPT-6.1 Sol.

## Is Fable 5.5 real? User reports and a reported Azure listing

Fable 5.5 may exist and be close to launch, but Anthropic hasn't said so. As of October 14, 2026:

- The [Anthropic newsroom](https://www.anthropic.com/news) has no Fable 5.5 post. Its latest model posts are Haiku 5.5 (October 7), Sonnet 5.5 (September 28), Opus 5.5 (September 22) and Fable 5.1 with Mythos 5.1 (September 1).
- The [Claude models overview](https://platform.claude.com/docs/en/models/overview) lists Fable 5.1, Opus 5.5, Sonnet 5.5 and Haiku 5.5, with Fable 5.1 as the current Fable. On October 6, a docs URL ending in `fable-5-5` loaded only the generic documentation shell, with no model name, specs or prices. A URL that loads is not a hidden model page.
- As of October 6, the [Claude API release notes](https://platform.claude.com/docs/en/release-notes/overview), the Claude apps release notes and the Claude status history contained no Fable 5.5 entry.

A Tuesday, October 6 release circulated as a rumor before that date. The day passed with no launch, and Anthropic never confirmed it.

What exists is a stream of user reports. Posts on X and Reddit say some accounts on claude.ai and in Claude Code are getting a newer model while the model picker still shows Fable 5.1. Users have shared a pixel-art game, an animated short with a score, motion design and 3D web pages. One tester says it is "outperforming Opus 5.5 and Astra too" in their own testing, especially for motion design and video editing. A Reddit thread notes that Opus 5.5 was "secretly tested" in a similar way 3–5 days before its release. That is a pattern people noticed, not a promise.

None of those posts shows a model ID, a request log or a statement from Anthropic. The demos are chosen by the people posting them, and you can't rerun them. A model that calls itself "Fable 5.5" when asked proves nothing about which model is serving the request. Treat the reports as a reason to expect a launch, not as a measurement. No benchmark of Fable 5.5 exists, and Artificial Analysis has no Fable 5.5 page. Any "Fable 5.5 is X% better" claim has nothing behind it yet.

The newest clue came from Microsoft's cloud. On October 13, Alex Getman (@alexgetmancom) flagged on X a `claude-fable-5-5` identifier tied to Azure, and [Runtime Wire's report on the Azure listing](https://runtimewire.com/article/anthropic-fable-5-5-azure-catalog-listing) traced it to a LiteLLM entry, `azure_ai/claude-fable-5-5`, pointing at an East US 2 endpoint. Reports disagree on whether the model showed up in Azure's catalog with a "GenerallyAvailable" status or only in metadata. One report says its prices and context length were copied from Fable 5.1. Runtime Wire calls it a credible infrastructure clue, not a launch. Here is what it can and can't tell you:

- **It suggests** that a model under that name is being prepared on at least one cloud.
- **It doesn't show** that anyone can call the model, what it costs, how it performs or when it launches. Prices copied from Fable 5.1 say nothing about Fable 5.5's real price.
- **Nobody has confirmed it.** Neither Microsoft nor Anthropic has commented.

Don't hardcode `claude-fable-5-5` because it appeared in a reported Azure entry. If Anthropic releases the model, take the ID from its model page.

## Fable 5.2 vs Fable 5.5: why this page once said 5.2

This page first appeared on September 20, when the same kind of rumor used a different number. On September 18–19, testers posted results from a "suspected next Fable" they called Fable 5.2, with claims that requests were moving "Fable 5.1 → 5.2." [JAZII's September 18 report](https://x.com/notjazii/status/2100940408624939447) said that with the same prompt and high reasoning, the output looked better than GPT-6 Astra's, but runs were slower and expensive. In a [follow-up post](https://x.com/notjazii/status/2100941084025290762), the author said "5.2" was their own assumption.

The Gemini side of those sightings came from Arena. A controller SVG that [Lumina compared with GPT-6 Astra's](https://x.com/LuminaBench/status/2101359620472115598) was attributed to Gemini 4 but appeared under an entry labeled `gemini 3.7 flash`. The author called both versions nearly perfect, and said they could not get similar results the next day.

Whether the September "5.2" model and today's "5.5" reports describe the same model is unknown. Whether the Arena output came from what Google later named Argon is also unknown. Anthropic has not renamed anything publicly. Both reports point to the same lesson: a stronger-looking first result can come with a longer wait and a higher bill, and one striking output is not a repeatable result.

![Two cards titled Alleged Gemini 4 and Suspected next Fable: one notes a controller SVG close to Astra and a repeatability question, the other notes stronger output that was slower and more expensive](https://blog.laozhang.ai/posts/en/gemini-4-vs-gpt-6-vs-fable-5-2/img/early-demo-signals.webp)

*This image summarizes the September 18–20 sightings. "Alleged Gemini 4" and "Suspected next Fable" are the labels used before Google named Argon and before the current Fable 5.5 reports.*

## Is Gemini 4 Argon out? Yes, generally available since October 13

Yes. Google [announced Gemini 4 Argon on September 30](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-4-argon/) and at first rolled it out only to "a set of trusted cyber defenders through our Fairwind Program." On October 13 it became generally available. The [Gemini API models page](https://ai.google.dev/gemini-api/docs/models) now lists `gemini-4-argon` as a stable model. "Gemini 4 Pro" was an earlier rumored name; the released model is Gemini 4 Argon.

Where you can use it, as of October 14, 2026:

- **Developers:** the Gemini API paid tier, Google AI Studio and Google's Gemini platform for enterprises. The [Gemini API pricing page](https://ai.google.dev/gemini-api/docs/pricing) says Argon is not on the free tier, and not on the API side of the Google AI Pro plan.
- **Gemini app and AI Mode in Search:** Google AI Pro and Ultra subscribers. That app access is separate from the API restriction above.
- **Google Antigravity:** Google AI Ultra subscribers and, as of October 16, 2026, paid Google AI Pro subscribers; as of October 23, 2026, a Pro trial also counts if it came with an eligible premium device. The [Antigravity models page](https://antigravity.google/docs/models) lists Argon in the Antigravity app, CLI and IDE extensions, not in the Antigravity IDE, and Pro access is still rolling out.
- **Gemini for business** on web, desktop and mobile.

It isn't free on the API. Standard pricing is $2 input and $10 output per million tokens, with cached input at $0.10, through November 30, 2026. From December 1, all three rates double to $4, $20 and $0.20. Batch and Flex cost half the standard rate. The context window of 1,048,576 tokens is shared by input and output. A normal synchronous call returns up to 65,536 output tokens, and a separate long-decode mode goes up to 1,048,576. Opus 5.5, Fable 5.1, GPT-6.1 Sol and GPT-6 Astra cap output at 128K. Google has not published Argon's rate limits.

Fairwind still exists, but now only for the version without cyber guardrails, which Google gives to approved defenders. The [Gemini 3.8 Flash Cyber Fairwind guide](https://blog.laozhang.ai/en/posts/gemini-3-8-flash-cyber-fairwind) explains how that program worked for 3.8 Flash Cyber. Google has not published separate application steps for Argon.

The published scores are strong but mixed:

- **Google's own table** compares Argon with GPT-6 Astra, Claude Fable 5.1 and Claude Opus 5.5. GPT-6.1 Sol is not in it. Argon leads Opus 5.5 on the Vals Index (68.9 vs 67.0) and DeepSWE v1.1 (77.9 vs 74.2). Opus 5.5 leads on FrontierSWE v2 (62.3 vs 55.0) and Terminal-bench 4.0 (66.4 vs 57.4).
- **Artificial Analysis Intelligence Index v4.3.2 at "high" effort** scores Argon 53 at $1.99 per index task, Opus 5.5 54 at $1.82 and GPT-6.1 Sol 50 at $0.32. Argon and Sol share the same $2 / $10 token price until November 30, yet $1.99 ÷ $0.32 ≈ 6.2, so Argon costs about six times more per task because it uses far more tokens. If its token use stays the same, Argon's cost per task would reach about $1.99 × 2 = $3.98 from December 1. Sol at max effort scores 52 for $0.72, within one point of Argon at high for about 36% of its current cost.
- **The Vals Index** ranks Argon first of 41 models at 68.90%, ahead of Opus 5.5 (66.97%), Fable 5.1 (65.83%), GPT-6 Astra (63.13%) and GPT-6.1 Sol (61.15%). Vals also lists Argon weak on CUA-bench, at 4.83%.

For access details, prices before and after December 1 and cost per task, see [Gemini 4 Argon vs Claude Opus 5.5 vs GPT-6.1 Sol: cost and access](https://blog.laozhang.ai/en/posts/gemini-4-argon-vs-claude-opus-5-5-vs-gpt-6-1-sol).

## What to run now while Fable 5.5 is out of reach

Don't pause real work waiting for Fable 5.5. Pick from the documented models by workload:

| If your work is mostly… | Run now | Why |
|---|---|---|
| Mixed coding, writing and agent tasks at frontier quality | Claude Opus 5.5 | $4 / $20 per million tokens; Anthropic says it performs at Fable 5.1's level on most work; Artificial Analysis puts it level with Argon at high effort |
| High volume or cost-sensitive work | GPT-6.1 Sol | $2 / $10 up to 272K input, and $0.32 per Artificial Analysis index task at high effort |
| Tasks where Argon's lead on the Vals Index and Google's table might matter, on the Gemini API | Gemini 4 Argon | Callable since October 13 at $2 / $10 through November 30, then $4 / $20; about $1.99 per Artificial Analysis index task at high effort, roughly six times GPT-6.1 Sol |
| The hardest reasoning and long-horizon agent jobs where Opus 5.5 at higher effort still falls short | Claude Fable 5.1 | The [Claude models overview](https://platform.claude.com/docs/en/models/overview) says to start with Opus 5.5 for most workloads and use Fable 5.1 for "demanding reasoning and long-horizon agentic work"; it costs $10 / $50 |
| Workflows already tuned for OpenAI's agentic model | GPT-6 Astra | Still available at $10 / $50 up to 272K input; see the [GPT-6 Astra API pricing guide](https://blog.laozhang.ai/en/posts/gpt-6-astra-api-pricing) |

Use the [Claude Fable 5.1 vs Opus 5.5 comparison](https://blog.laozhang.ai/en/posts/claude-fable-5-1-vs-opus-5-5) if the choice is between the two Claude models, and [Claude Fable 5.1 API pricing](https://blog.laozhang.ai/en/posts/claude-fable-5-1-api-pricing) for its full billing details.

Argon you can test now. If price matters, measure it before December 1 and recompute its cost at $4 / $20, since results gathered at the introductory rate will understate what you pay later. For Fable 5.5, the useful thing to do while you wait is to build your test set now. When it becomes available, you can run it against your current model right away instead of starting the evaluation from scratch.

## Release-day checklist: signs Fable 5.5 is actually available

Count a model as released only when it appears on the vendor's own pages and in your account.

**For Claude Fable 5.5:**

1. A launch post in the [Anthropic newsroom](https://www.anthropic.com/news).
2. A model page with real content and a pricing row on the Claude Platform docs, with an exact model ID.
3. An entry in the [Claude API release notes](https://platform.claude.com/docs/en/release-notes/overview).
4. The ID in the `GET /v1/models` response for your own API key. The list is paginated, so check every page before deciding the model is missing.
5. For app users, the name in the claude.ai model picker. Output that seems better, or a model that names itself, doesn't count.

**Cloud catalog sightings,** like the reported Azure entry, sit between rumor and release. Treat one as confirmed only when the cloud provider's own model documentation lists the model and a request from your own account succeeds. A string in a third-party library config such as LiteLLM, or prices copied from an older model, doesn't meet that bar.

**Gemini 4 Argon already passed this kind of check on October 13:** a model ID on the Gemini API models page, a pricing row with the November 30 end of the introductory price, and the model in the Gemini app for Google AI Pro and Ultra subscribers.

Social posts about being routed to a new model, leaked screenshots and URLs that merely load don't meet any of these checks.

## How to compare Fable 5.5, Argon and your current model fairly

Argon can go through this comparison now; Fable 5.5 can once it meets the checklist. Compare them on your own work rather than on demos:

- **Identified models.** Use the documented model ID for every run, and record it with the results.
- **Matched tasks.** Use the same task description, files, tools and permissions for every model.
- **Matched effort or budget.** Comparing one model at max effort with another at high effort shows you the effort setting, not the model.
- **Acceptance criteria written in advance.** Decide what counts as done, such as passing tests, following the required format or needing only minimal edits, before you see any output.
- **Every attempt counted.** Record retries, total cost and wall-clock time, not just the best run.

Then compare cost per accepted task, which equals the cost of all attempts divided by the number of accepted tasks. For example, if 25 attempts cost $30 in total and 20 tasks pass review, the cost is $30 ÷ 20 = $1.50 per accepted task. A pricier model can come out cheaper on this measure if it needs fewer retries. A model that produces richer output can come out more expensive if the extra material has to be removed. For Argon, run the same calculation at the December 1 prices too. All its token rates double, so if that $1.50 came from Argon today, the same attempts would cost $3.00 per accepted task from December 1.

![Flowchart that sends the same task and inputs to a current model and to GPT-6 Astra, then checks whether the result meets the requirement, how long review takes and the total cost including retries](https://blog.laozhang.ai/posts/en/gemini-4-vs-gpt-6-vs-fable-5-2/img/task-evaluation.webp)

*This chart was made in September with GPT-6 Astra as the comparison model. Its note about "Gemini 4 and Fable 5.2" refers to the earlier rumor names and predates Argon's documentation on October 13. The same steps apply with Opus 5.5, Fable 5.1 or GPT-6.1 Sol as your baseline and Argon, or later Fable 5.5, as the challenger.*

A launch announcement settles the names, the IDs and the prices. Only a repeatable improvement on your own tasks tells you whether to switch.

## Sources

External pages this guide links to, in the order they appear. Last updated 2026-10-16.

- [Anthropic newsroom](https://www.anthropic.com/news) (anthropic.com)
- [Claude models overview](https://platform.claude.com/docs/en/models/overview) (platform.claude.com)
- [Google's Gemini 4 Argon launch post](https://blog.google/innovation-and-ai/models-and-research/gemini-models/introducing-gemini-4-argon/) (blog.google)
- [Gemini API pricing page](https://ai.google.dev/gemini-api/docs/pricing) (ai.google.dev)
- [OrcaRouter's account of the leak chain](https://www.orcarouter.ai/blog/claude-fable-5-5-leak) (orcarouter.ai)
- [Claude API release notes](https://platform.claude.com/docs/en/release-notes/overview) (platform.claude.com)
- [Runtime Wire's report on the Azure listing](https://runtimewire.com/article/anthropic-fable-5-5-azure-catalog-listing) (runtimewire.com)
- [JAZII's September 18 report](https://x.com/notjazii/status/2100940408624939447) (x.com)
- [follow-up post](https://x.com/notjazii/status/2100941084025290762) (x.com)
- [Lumina compared with GPT-6 Astra's](https://x.com/LuminaBench/status/2101359620472115598) (x.com)
- [announced Gemini 4 Argon on September 30](https://blog.google/innovation-and-ai/models-and-research/gemini-models/gemini-4-argon/) (blog.google)
- [Gemini API models page](https://ai.google.dev/gemini-api/docs/models) (ai.google.dev)
- [Antigravity models page](https://antigravity.google/docs/models) (antigravity.google)