Anthropic
Anthropic's most capable widely released model for demanding reasoning and long-horizon agentic work. It is proprietary, generally available through the Claude API and supported cloud platforms, and cannot run locally as an open-weight model.
Anthropic's most capable widely released model for demanding reasoning and long-horizon agentic work.
68.9
Quality Score
1313
Arena ELO
Undisclosed
Parameters
1M
Context
This measures the amount of verifiable public evidence we have, not how capable the model is. A missing field means it has not been verified yet, not that its value is zero.
18 of 22 public signals
Use this section to answer one simple question first: how much outside evidence do we have that this model performs well? Structured benchmark scores appear first, then official provider evidence, then live arena signal.
This model has normalized benchmark rows, so scores here are directly comparable across benchmark sources.
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26.8K
Downloads
0
Likes
Jun 2026
Released
4/5 signals
4/4 signals
5/5 signals
2/4 signals
3/4 signals
Parameters
—
Training compute
Not reported
Dataset scale
Not reported
Base model
Not reported
Source-reported access: API access · Confident confidence
Gaps we are still tracking
These are recent benchmark or leaderboard claims from official provider sources. They are useful for freshness and context, but they are not treated the same as normalized independent benchmark rows.
Claude Fable 5 and Claude Mythos 5 System Card
Anthropic reports Claude Fable 5 production-safeguard results for coding, terminal, and computer-use evaluations in its official system card.
View source1313
ELO Score
1305 - 1321
95% Confidence
+/-8 points
10.0K
Battles
Sep 5, 2026
Last Updated