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Model

Claude Fable 5 NO.01

Anthropic's most capable model — the reliability frontier for the hardest agentic work.

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Anthropic · Claude · Frontier · Closed weights

Specification

Fig.01 — Claude — Anthropic

USA

Context window
1Mtokens
Max output
128Ktokens
Input price
$10/ 1M
Output price
$50/ 1M
Cached input
$1/ 1M
Throughput
—
Class
Frontier
Modalities
Text, Image, Pdf
Weights
Closed
Knowledge cutoff
Feb 2026
Released
Jun 2026

Overview

Claude Fable 5 is Anthropic's most capable widely-released model and the current reliability frontier for the hardest long-horizon agentic tasks. It sustains multi-hour autonomous coding sessions without derailing, corrupting a codebase, or looping, and holds coherence across its full million-token context. It is the model practitioners reach for when a complex agentic job absolutely must complete correctly.

Strengths

  • Best-in-class long-horizon agentic reliability
  • Elite real-world coding and multi-file refactoring
  • Sustained coherence over a 1M-token context
  • Exceptional instruction following and tool use
  • Strong scientific and graduate-level reasoning

Trade-offs

  • Highest price in the Claude lineup
  • Slower than smaller Claude models
  • No audio or video input
  • Output capped at 128K tokens
  • Overkill for routine or high-volume workloads

Fit

Best for

  • Autonomous multi-hour coding agents
  • Large-scale codebase migrations and refactors
  • Complex multi-step research and analysis
  • High-stakes agentic workflows
  • Hard reasoning and planning problems

Not ideal for

  • High-volume cheap classification
  • Latency-critical realtime chat
  • Simple one-shot tasks where cost matters

Capabilities

Ten axes, normalized 0–100 and scored the same way across the whole catalog — so a 78 here means what a 78 means anywhere else on the bench.

Fig.02 — Capability radar

0 — 100

Reasoning
97
Coding
98
Math
94
Writing
95
Knowledge
94
Speed
45
Agentic
98
Vision
89
Multilingual
92
Long Context
96

Benchmarks

Public results, with independent third-party runs marked. Bars normalize percentages against 100 and Elo ratings against a 1500 ceiling.

Independent index

Artificial Analysis Intelligence Index

Composite of ~9–10 independent evals · Artificial Analysis

60/ 100

BenchmarkResult
Artificial Analysis Intelligence IndexIndependentGeneral · Artificial Analysis
60%
SWE-bench VerifiedIndependentCoding · SWE-bench
95%
SWE-bench ProIndependentCoding · SWE-bench Pro
80%
τ-benchIndependentAgentic · τ-bench
89.2%
LiveBenchIndependentGeneral · LiveBench
78.3%
GPQA DiamondIndependentReasoning · Independent aggregators
94.1%
Terminal-Bench HardIndependentAgentic · Artificial Analysis
62.9%
LMArena EloIndependentGeneral · LMArena
1525Elo

Alternatives

Models in roughly the same class — the ones worth weighing against this record.

Compare side by side
01Claude Opus 4.8AnthropicState-of-the-art autonomous coding reliability at half the price of Fable 5.02GPT-5.6 SolOpenAIOpenAI's GPT-5.6 flagship — its best coding-and-agentic model yet, for the hardest work.03GPT-5.6 Sol UltraOpenAISol's maximum-compute mode — cooperating sub-agents for the hardest multi-step work.

Index

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