---
title: "Claude Fable 5.1 AI model: facts and benchmarks | Kendr"
canonical: "https://kendr.org/models/anthropic-claude-fable-5-1"
date_modified: "2026-09-06"
profile_kind: "reference"
---

# Claude Fable 5.1 model profile

Claude Fable 5.1 is a Anthropic model profile with a 1,000,000-token context window. The dated catalog snapshot records text, image, file modalities and interfaces for file input, prompt caching, reasoning controls, structured output, text generation.

Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual code generation, and finance and analysis tasks in particular. It also tends to be more concise than Fable 5 in its plans and summaries. We recommend testing it as a direct upgrade wherever you use Fable 5 today, and alongside Opus 5 on reasoning-heavy tasks.

Claude Fable 5.1 is a reference profile: Anthropic publishes it, Kendr documents it for comparison, and it carries no Kendr alias to call.

Claude Fable 5.1 is an independent knowledge profile. It does not claim that Kendr hosts the model, quote a Kendr customer price, promise API availability, or advertise a Kendr routing receipt.

Claude Fable 5.1 accepts text, image, and file and returns text. The snapshot records file input, prompt caching, reasoning controls, structured output, text generation, tool calling, vision, and web search pricing as capabilities or interfaces.

The dated reference snapshot lists $10 input and $50 output per million tokens. Cached input is $0.25 per million tokens.

The 2026-09-06 snapshot includes 3 Artificial Analysis indexes, 7 Design Arena categories, and AutoExacto results for 4 provider observations. Publisher-reported launch results are labeled and are not presented as Kendr measurements; scores from different suites are not treated as interchangeable.

Claude Fable 5.1 ranked #45 in the cited trailing-7-day third-party catalog usage dataset as of 2026-09-06. Observed within the cited trailing-7-day third-party catalog usage dataset; this is not global AI market share.

Profile data was reviewed for the 2026-09-06 snapshot. Claims retain their source dates, and unavailable fields are shown as unavailable instead of estimated.

## Profile facts

- **Profile type:** Model research profile
- **Provider or publisher:** Anthropic
- **Context window:** 1,000,000 tokens
- **Snapshot date:** 2026-09-06
- **Knowledge cutoff:** Not disclosed
- **Reference catalog ID:** anthropic/claude-fable-5.1

## When to pick Claude Fable 5.1

Claude Fable 5.1 is a reference profile: Anthropic publishes it, Kendr documents it for comparison, and it carries no Kendr alias to call.

Each condition below is derived from this model's own values in the 2026-09-06 snapshot, compared only against models publishing the same field.

- Reach for it when answer quality matters more than unit cost. It scores 56.8 on the Artificial Analysis intelligence index, above three quarters of the 32 models carrying that field in the 2026-09-06 snapshot.
- Reach for it when the input includes images. The snapshot records image input, so screenshots, scans, and diagrams can be sent directly instead of described.
- Reach for it when the model has to call tools. Tool calling is recorded in the snapshot, so this route can drive an agent loop rather than only answer in prose.
- Look elsewhere when you need to call it through Kendr today. This is a research reference profile with no Kendr alias. The facts and evidence here are published for comparison; the model is not routable on Kendr.
- Look elsewhere when the work does not justify the rate. At $10 in and $50 out per 1M tokens, this is in the most expensive tenth of the 146 models publishing both rates. Route routine or high-volume traffic to a cheaper model and keep this one for work that needs it.
- Look elsewhere when the request is trivial and latency-sensitive. Reasoning is mandatory on this route and cannot be turned off, so short factual requests still pay reasoning tokens and reasoning latency.

## Context, modalities, and identity

Claude Fable 5.1 accepts text, image, and file and returns text. The snapshot records file input, prompt caching, reasoning controls, structured output, text generation, tool calling, vision, and web search pricing as capabilities or interfaces.

- **Provider or publisher:** Anthropic
- **Context window:** 1,000,000 tokens
- **Maximum output:** 128,000 tokens
- **Input modalities:** text, image, and file
- **Output modalities:** text
- **Knowledge cutoff:** Not disclosed

## Model overview

Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual code generation, and finance and analysis tasks in particular. It also tends to be more concise than Fable 5 in its plans and summaries. We recommend testing it as a direct upgrade wherever you use Fable 5 today, and alongside Opus 5 on reasoning-heavy tasks.

- **Reference model ID:** anthropic/claude-fable-5.1
- **Canonical version:** anthropic/claude-fable-5.1-20260831
- **Hugging Face ID:** Not separately documented

## Capabilities and supported controls

Capabilities and parameters are reported from the dated catalog and source records; their presence does not guarantee identical behavior across every provider route.

- **Supported parameters:** include_reasoning, max_completion_tokens, max_tokens, reasoning, reasoning_effort, response_format, stop, structured_outputs, tools, verbosity

- file input
- prompt caching
- reasoning controls
- structured output
- text generation
- tool calling
- vision
- web search pricing

## Dated pricing snapshot

The dated reference snapshot lists $10 input and $50 output per million tokens. Cached input is $0.25 per million tokens.

These are dated third-party reference prices, not Kendr prices or an availability offer. Routes, tiers, caching, region, and provider policy can change the landed price.

- **Price date:** 2026-09-06
- **Input:** $10 per 1M tokens
- **Cached input:** $0.25 per 1M tokens
- **Output:** $50 per 1M tokens

## Provider routes, performance, and uptime

The snapshot retains 4 provider endpoints. Provider prices, context limits, p50 performance, and uptime can differ by route and are not Kendr guarantees.

- **Active provider endpoints:** 4
- **Best p50 latency:** 3.30 s
- **Best p50 throughput:** 53 tok/s
- **Availability with routing:** 99.95% over the sampled window
- **Availability without routing:** 97.09% over the sampled window
- **Performance date:** 2026-09-06

| Provider | Quantization | Input / 1M | Output / 1M | Cache read / 1M | Context | p50 latency | p50 throughput | Uptime (1d) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Azure | unknown | $10 / 1M | $50 / 1M | $0.25 / 1M | 1,000,000 tokens | 7.35 s | 38 tok/s | 99.61% |
| Anthropic | unknown | $10 / 1M | $50 / 1M | $0.25 / 1M | 1,000,000 tokens | 6.28 s | 47 tok/s | 99.90% |
| Amazon Bedrock (BYOK Only) | unknown | $10 / 1M | $50 / 1M | $0.25 / 1M | 1,000,000 tokens | 3.30 s | 52 tok/s | No recent uptime |
| Google Vertex | unknown | $10 / 1M | $50 / 1M | $0.25 / 1M | 1,000,000 tokens | 4.17 s | 53 tok/s | 99.66% |

## Benchmark evidence and limitations

The 2026-09-06 snapshot includes 3 Artificial Analysis indexes, 7 Design Arena categories, and AutoExacto results for 4 provider observations. Publisher-reported launch results are labeled and are not presented as Kendr measurements; scores from different suites are not treated as interchangeable.

Third-party catalog fields normalized from the cited model dataset; benchmark methodology and coverage differ by source.

- **Intelligence Index:** 56.8
- **Coding Index:** 81.6
- **Agentic Index:** 58.2
- **AutoExacto coverage:** 4 provider observations over 32 days

| Design Arena category | Elo | Win rate | Rank |
| --- | --- | --- | --- |
| 3d | 1432 | 70.3% | #2 |
| codecategories | 1345 | 59.4% | #3 |
| dataviz | 1370 | 63.7% | #1 |
| gamedev | 1432 | 69.8% | #1 |
| svg | 1359 | 65.6% | #2 |
| uicomponent | 1336 | 58.2% | #7 |
| website | 1321 | 56.4% | #4 |

## AutoExacto provider benchmarks

Rolling provider observations from the cited third-party benchmark view. The lookback is 32 days; GPQA Diamond and TAU-Bench Airline measure different abilities and should not be blended into one score.

| Provider | GPQA Diamond | TAU-Bench Airline | Runs |
| --- | --- | --- | --- |
| Anthropic | 86.47% | 79.33% | 2 |
| auto-routing | 90.91% | — | 1 |
| Azure | 86.28% | 74.67% | 2 |
| Google Vertex | 84.89% | 76.67% | 2 |

## Popularity and market context

Claude Fable 5.1 ranked #45 in the cited trailing-7-day third-party catalog usage dataset as of 2026-09-06. Observed within the cited trailing-7-day third-party catalog usage dataset; this is not global AI market share.

- **Third-party catalog rank:** #45
- **Global market share:** Not inferred
- **Observation date:** 2026-09-06

## Frequently asked questions

### When should I use Claude Fable 5.1?

Claude Fable 5.1 is a reference profile: Anthropic publishes it, Kendr documents it for comparison, and it carries no Kendr alias to call. Reach for it when answer quality matters more than unit cost: It scores 56.8 on the Artificial Analysis intelligence index, above three quarters of the 32 models carrying that field in the 2026-09-06 snapshot. Reach for it when the input includes images: The snapshot records image input, so screenshots, scans, and diagrams can be sent directly instead of described. Reach for it when the model has to call tools: Tool calling is recorded in the snapshot, so this route can drive an agent loop rather than only answer in prose. Look elsewhere when you need to call it through Kendr today: This is a research reference profile with no Kendr alias. The facts and evidence here are published for comparison; the model is not routable on Kendr. Look elsewhere when the work does not justify the rate: At $10 in and $50 out per 1M tokens, this is in the most expensive tenth of the 146 models publishing both rates. Route routine or high-volume traffic to a cheaper model and keep this one for work that needs it. Look elsewhere when the request is trivial and latency-sensitive: Reasoning is mandatory on this route and cannot be turned off, so short factual requests still pay reasoning tokens and reasoning latency.

### What is Claude Fable 5.1?

Claude Fable 5.1 is a Anthropic model profile with a 1,000,000-token context window. The dated catalog snapshot records text, image, file modalities and interfaces for file input, prompt caching, reasoning controls, structured output, text generation.

### What context window does Claude Fable 5.1 have?

The dated profile lists 1,000,000 tokens of context and up to 128,000 output tokens. Provider routes, variants, and runtime configuration can impose lower effective limits.

### What benchmark evidence is available for Claude Fable 5.1?

The 2026-09-06 snapshot includes 3 Artificial Analysis indexes, 7 Design Arena categories, and AutoExacto results for 4 provider observations. Publisher-reported launch results are labeled and are not presented as Kendr measurements; scores from different suites are not treated as interchangeable. Third-party catalog fields normalized from the cited model dataset; benchmark methodology and coverage differ by source.

### Is Claude Fable 5.1 available through Kendr?

This is an independent knowledge profile, not a Kendr-hosted availability claim. Check Kendr's live public model API for currently enabled Kendr aliases.

### Does the popularity rank represent Claude Fable 5.1's global market share?

Claude Fable 5.1 ranked #45 in the cited trailing-7-day third-party catalog usage dataset as of 2026-09-06. Observed within the cited trailing-7-day third-party catalog usage dataset; this is not global AI market share. No global market-share percentage is inferred when the source does not publish one.

## Sources and evidence dates

- [Claude Fable 5.1 third-party catalog record](https://openrouter.ai/anthropic/claude-fable-5.1) — catalog, checked 2026-09-06
- [Third-party model catalog methodology](https://openrouter.ai/docs/guides/overview/models) — methodology, checked 2026-09-06
- [Anthropic official model documentation](https://platform.claude.com/docs/en/about-claude/models/overview) — primary, checked 2026-09-06
- [Artificial Analysis capability indices methodology](https://artificialanalysis.ai/methodology/capability-indices) — benchmark, checked 2026-09-06
- [Design Arena leaderboard and methodology](https://www.designarena.ai/leaderboard) — benchmark, checked 2026-09-06
- [Claude Fable 5.1 third-party catalog record](https://openrouter.ai/blog/announcements/auto-exacto/) — benchmark, checked 2026-09-06

Live Kendr operational availability is published separately at https://api.kendr.org/api/public/models.