Previous-generation ID
Claude API
Existing integrations can verify claude-fable-5 in the Models API. New evaluations should compare the current claude-fable-5-1 ID, account eligibility, effort defaults, rate limits, pricing, and data controls.
Anthropic model · checked September 2, 2026 Previous generation · 5.1 is current
Quick answer
Fable 5 is now a migration record for the 5.1 generation.
Fable 5 remains relevant to existing integrations, but Anthropic now names Fable 5.1 as the current generally available model. Compare IDs, cache pricing, safeguards, effort defaults, and Enterprise Frontier Safeguards before migrating.
Verified provider record
Provider status
Previous generation. Anthropic introduced Fable 5.1 as the current generally available model on September 1, 2026; verify the live catalog before starting a new Fable 5 deployment.
Claude API ID
claude-fable-5. Anthropic documents dateless IDs from this generation as pinned snapshots, not evergreen aliases.
Inputs and output
Text and image input, text output, multilingual capability, and vision.
Context and output
1 million token context window and up to 128,000 output tokens in the synchronous Messages API.
Published API price
$10 per million input tokens and $50 per million output tokens. Fable 5.1 keeps those base rates but cuts its cache-read rate to $0.25 per million tokens; do not apply that cache price to Fable 5 without a live billing check.
Flowith access
Not asserted here. Anthropic availability does not establish a Flowith workspace model mapping.
Access map
General availability does not mean one entitlement
Live selector required
Claude apps and Code
The July 20 Fable 5 plan rules remain useful history, but model generation, included usage, effort default, and credits must be checked in the current product and governing plan.
Provider-dependent
AWS, Google Cloud, and Azure
Anthropic lists Fable 5.1 across AWS, Google Cloud, and Microsoft Azure. Historical Fable 5 IDs, regions, quotas, contracts, and data routing still belong to each platform.
Verify separately
Flowith
Check the live Flowith model selector and account entitlements. Provider release state alone is not evidence of integration.
Safeguard and data boundaries
- Fable 5 and Mythos 5 shared one underlying model. Anthropic now describes the same relationship for Fable 5.1 and Mythos 5.1, making 5.1 the current comparison generation.
- Fable 5.1 permits vulnerability discovery but continues to redirect penetration testing, exploit generation, binary-based vulnerability scanning, and other dual-use work to Opus models.
- Anthropic reports about 60% fewer cyber-safeguard interventions per Claude Code session than the prior Fable 5 safeguards. That is provider evaluation evidence, not a guarantee for one workload.
- Anthropic says its latest biology safeguards for Fable 5.1 and Fable 5 fire 85% less often on benign elementary biology and medical questions, while professional life-sciences work can still be redirected.
- Enterprise Frontier Safeguards is a phased, opt-in architecture: monitoring data can stay in customer-controlled cloud storage under customer keys, with flags sent to the customer's reviewers and no Anthropic human review required.
- Eligible customers can use Fable 5 and Fable 5.1 with zero data retention until EFS is ready. EFS availability, storage cost, rollout phase, and covered surface still require contract and live-account verification.
Official sources
- Fable 5.1 and Mythos 5.1 launch — current generation, shared model, access profiles, API ID, cache-read pricing, and safeguard changes.
- Enterprise Frontier Safeguards — phased rollout, customer-controlled storage, automated monitoring, review ownership, supported surfaces, and cloud costs.
- Anthropic launch — shared model, safeguards, launch pricing, capabilities, and data policy.
- Anthropic redeployment update — suspension, restoration, global Fable access, and Mythos restrictions.
- Biology safeguard update — current Opus 5 fallback, fewer false positives, expanded benign use, and remaining dual-use boundaries.
- Claude model overview — current IDs, limits, pricing, modalities, cloud surfaces, and versioning.
- Fable 5 plan guide — current plan inclusion and usage-credit rules from July 20.
Continue by decision intent
Plans and 5.1 migration Separate the July Fable 5 plan record from the current 5.1 API, cache-price, and entitlement checks. Fable vs Mythos Compare safeguards, fallback behavior, trusted access, and data boundaries. Claude Mythos 5 Understand the previous restricted model and the current Mythos 5.1 trusted-program boundary. Claude Opus 5 Consider the generally available enterprise model when Fable safeguards or cost do not fit.
Claude Fable 5 questions, answered
Claude Fable 5 is the previous broadly released Fable generation. It shares its underlying model with Claude Mythos 5 but adds conservative safeguards for general access. Anthropic introduced Fable 5.1 as the current generally available generation on September 1, 2026.
Anthropic documents claude-fable-5. In this model generation, a dateless Claude model ID is a pinned snapshot rather than an evergreen pointer.
Anthropic documented a 1 million token context window, up to 128,000 output tokens in the synchronous Messages API, and base API pricing of $10 per million input tokens and $50 per million output tokens. Fable 5.1 keeps those base rates but has a separate $0.25 cache-read rate.
From July 20, 2026, Anthropic says Pro uses Fable 5 through pay-as-you-go usage credits from the start. Max and premium Team or legacy Enterprise seats can use up to 50% of their shared weekly limit on Fable before credits.
They share the same underlying model and published specifications, but Fable adds conservative safeguards and fallback behavior for broad access. Mythos has safeguards lifted in approved domains and remains restricted to trusted organizations.
Anthropic's August 7, 2026 update says a triggered biology request is rerouted to Claude Opus 5. The narrower classifier allows more benign health, education, and clinical work, while dual-use professional biology and drug-development requests can still fall back.
Evaluate Fable 5.1 first. Anthropic identifies claude-fable-5-1 as the current generally available API model and says it keeps Fable 5's $10 input and $50 output base rates while reducing cache reads to $0.25 per million tokens. Keep Fable 5 only where compatibility testing or a governing contract requires it.
No. EFS is a phased, opt-in system. Eligible customers can use Fable 5 or Fable 5.1 with zero data retention during the transition, while EFS can store monitoring data in customer-controlled cloud infrastructure. Confirm rollout, storage, review, and contract details for the exact surface.
This page does not claim a Flowith model mapping. Verify the current Flowith workspace separately from Anthropic's API, apps, plans, and cloud platforms.