effort controlled · default high
Only provider-documented reasoning controls are shown; missing controls remain unpublished rather than inferred.
MODEL REFERENCE / ANTHROPIC
Claude Mythos 5.1
verified model reference.
Invite-only Project Glasswing counterpart to Claude Fable 5.1 for approved cybersecurity and biology research programs.
1,000,000context tokens
128,000max output
2026-10-07last verified
PRIMARY-SOURCE VERIFIED
Claude Mythos 5.1 at a glance.
Anthropic documents a 1,000,000-token context window. Input modalities: text + image. Output: text. Pricing status: Official paid API.
MODEL IDclaude-mythos-5-1
CONTEXT WINDOW1,000,000tokens
MAX OUTPUT128,000
KNOWLEDGE CUTOFF2026-06
STANDARD INPUT$10.00per 1 million tokens
STANDARD OUTPUT$50.00per 1 million tokens
CAPABILITY CONTRACT
Published model behavior.
text + image
Input modalities come from the cited official model documentation.
text
Output modality and output-limit claims remain separate so an undocumented token cap is not guessed.
PRICING STATUS
Official paid API.
$10.00 input · $0.25 cached · $50.00 output per 1 million tokens.
SXF preserves the provider-published native billing basis. Only calculator-eligible generative token models enter token-cost arithmetic; specialist units and input-only embeddings remain visible without forced conversion.
CAVEATS
What the source record does not assume.
01
Active invite-only model released September 1, 2026; retirement not sooner than September 1, 2027.
EXPLORE
Keep the model in context.
OFFICIAL SOURCES
Verification links.
WHAT CHANGED
Claude Mythos 5.1: what changed.
No post-baseline factual changes recorded for Claude Mythos 5.1 since 2026-10-07.
VERIFIED BASELINE2026-10-07Current facts remain aligned with the SXF ledger.
VERIFIED CHANGE HISTORY
Claude Mythos 5.1 verified history.
Claude Mythos 5.1
Baseline verified: 1,000,000 context · 128,000 max output · $10.00 input / $0.25 cached / $50.00 output per 1 million tokens
Official evidence ↗Append-only SXF ledger · 1 verified event · chain head 8e73a9cb15ea…