Claude Fable 5.1 model profile

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

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

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.

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

Sources and evidence dates

1. Claude Fable 5.1 third-party catalog record (catalog, checked 2026-09-06)
2. Third-party model catalog methodology (methodology, checked 2026-09-06)
3. Anthropic official model documentation (primary, checked 2026-09-06)
4. Artificial Analysis capability indices methodology (benchmark, checked 2026-09-06)
5. Design Arena leaderboard and methodology (benchmark, checked 2026-09-06)
6. Claude Fable 5.1 third-party catalog record (benchmark, checked 2026-09-06)