Claude Fable 5 vs Mythos 5: The Model Anthropic Locked Away

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Anthropic just shipped two near-identically named frontier models — Claude Fable 5 and Claude Mythos 5 — and the marketing barely explains the difference. One you can use today. The other is gated behind Project Glasswing and reserved for vetted partners. Same underlying model, two deployment modes, very different rules.
In this video I cut through the launch-day noise: what Anthropic actually released, what the independent benchmarks say versus the press release, why there are two versions, what it costs, who can access it, how to actually get value out of it as a builder — and the honest answer to whether this is AGI. No hype, just the evidence.
Topics covered

What Fable 5 and Mythos 5 actually are (and why they’re the same model)
CursorBench 3.1 results — 72.9% vs Opus 4.8, Opus 4.7, GPT-5.5
Databricks OfficeQA Pro — the speed and token-cost trade-off
Project Glasswing, the UK AISI cyber evaluation, and the bio-research angle
Pricing breakdown: $10 / $50 per million tokens vs Opus 4.8
How to actually deploy Fable 5 — effort levels, boundaries, verification
Is this AGI? The honest read

Chapters
00:00 The two-model problem nobody’s explaining
01:06 What Anthropic actually launched
02:42 What it can do — and what the benchmarks actually show
04:56 The cost of all that autonomy
06:44 Why there are two versions — the safety story
08:32 Pricing and access
09:54 Getting the most out of it
10:45 So — is it AGI?
12:34 The takeaway

Watch next
→ https://youtu.be/9y098u_GjKU
→ https://youtu.be/ks_0xYs1YG8
→ https://youtu.be/UQzHGL-Ci7U
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Sources / further reading
Anthropic — Claude Fable 5 & Mythos 5 documentation
Anthropic — Project Glasswing program page
Cursor — CursorBench 3.1 results
Databricks — OfficeQA Pro benchmark
UK AI Security Institute — Mythos Preview evaluation
CodeRabbit — Fable 5 code-review analysis

#ClaudeMythos5 #ClaudeFable5 #anthropic