Claude Fable 5 vs Claude Mythos 5
The newest Anthropic model — first Mythos-class made generally available. vs Restricted-access flagship — vetted partners only.
What I tested — same prompt, two models
I run the same fixed prompt set through every new model the day it drops — same string, one shot, single HTML file out — and I score the result 0–10 on whether it ran, how close it hit the brief, and how good it looked. Below is what came out when I gave the exact same prompts to Claude Fable 5 and Claude Mythos 5, side by side, on 0 shared tasks inside the Agent Operating System.
Both models were given identical prompts inside the Agent Operating System — no help, no iteration, no "best of N" tricks. I run each prompt once, save the HTML file the model produces, and score it 0–10 on whether it ran, how close it hit the brief, and how good it looked. The scoring is mine. The verdicts below are pulled from my source comparison guides at agentos.guide where I publish every score and the reasoning behind it.
Claude Fable 5 · Selected from Agent OS for the highest-stakes one-shot work — replacing Opus 4.8 as the safety net on hard prompts. Bench scoring pending.
Claude Mythos 5 · Not currently dispatched from Agent OS — no public API. Tracked for news coverage only.
Side-by-side on 0 shared tasks
Click any cell to play that model's actual one-shot attempt. Medals are derived from my 0–10 scores per task (highest = 🥇, second = 🥈, third = 🥉).
Strengths & weaknesses I logged
Claude Fable 5
Strengths
- Anthropic's most capable publicly-available model — vendor claim: 'capabilities exceed those of any model we've ever made generally available'
- Tops external SWE-bench Verified at 95.0% in Julian's three-dragons writeup
- Top-tier plan quality (9.1/10) on Kilo's plan-vs-build rubric
Trade-offs
- No goldiebench per-task scores yet — bench rank pending a published head-to-head guide
- Premium pricing; Fusion premium panel reportedly out-scores it at half the API cost
Claude Mythos 5
Strengths
- Highest-class Anthropic model — sits above Fable 5 in the Mythos line
- Same Mythos-class capability profile as Fable 5 (with restrictions)
Trade-offs
- No public API access — can't be benched against the open field
- Restricted distribution makes it effectively unavailable to most builders
Pricing & context — the spec sheet
| Spec | Claude Fable 5 | Claude Mythos 5 |
|---|---|---|
| Vendor | Anthropic | Anthropic |
| Context window | 200,000 tokens (1M with extended thinking) | 200,000 tokens |
| Price | Anthropic API pricing | Restricted access — vetted partners only |
| Pricing detail | Released alongside Mythos 5 on June 9, 2026 as the publicly-available member of the new Mythos class. Premium per-token pricing on the Anthropic API; available everywhere Opus 4.8 ships. | Mythos 5 is the un-released sibling of Fable 5. Same Mythos class, restricted to vetted partners. Made headlines mid-June 2026 when reports of a White-House-driven ban over China access dominated AI press. |
| Release | 2026-06-09 | 2026-06-09 |
| Bench coverage | 0/0 scored · avg — | 0/0 scored · avg — |
The verdict — which should you pick?
Not enough scored shared tasks yet for a head-to-head average. The live demos for both are on the matrix above — play them and form your own opinion.
If you only run one of these inside your stack, the head-to-head average above is the call. If you can run both, my honest play is to wire Claude Fable 5 and Claude Mythos 5 both into the Agent Operating System and dispatch each from the kanban by task type — mission-critical one-shot builds where you want anthropic's newest reasoning → Claude Fable 5, vetted enterprise partners with mythos-class access → Claude Mythos 5. That's the same setup I run for the 3,600+ founders inside the AI Profit Boardroom.
FAQ — Claude Fable 5 vs Claude Mythos 5
Which is better, Claude Fable 5 or Claude Mythos 5?
On Goldie Bench, Claude Fable 5 averages no scored verdicts yet across the shared tasks, with 0 gold, 0 silver, 0 bronze overall. Claude Mythos 5 averages no scored verdicts yet, with 0 gold, 0 silver, 0 bronze. Not enough scored shared tasks yet to call a winner.
How much does Claude Fable 5 cost vs Claude Mythos 5?
Claude Fable 5: Released alongside Mythos 5 on June 9, 2026 as the publicly-available member of the new Mythos class. Premium per-token pricing on the Anthropic API; available everywhere Opus 4.8 ships. Claude Mythos 5: Mythos 5 is the un-released sibling of Fable 5. Same Mythos class, restricted to vetted partners. Made headlines mid-June 2026 when reports of a White-House-driven ban over China access dominated AI press.
What's the context window for Claude Fable 5 vs Claude Mythos 5?
Claude Fable 5 has a 200,000 tokens (1M with extended thinking) context window. Claude Mythos 5 has a 200,000 tokens context window.
When should I pick Claude Fable 5 over Claude Mythos 5?
Pick Claude Fable 5 for: Mission-critical one-shot builds where you want Anthropic's newest reasoning; Long-context work using extended thinking up to 1M tokens; Plan-heavy multi-step tasks where intelligence in the plan matters more than the build. The trade-off is the weaknesses we logged on the bench: No goldiebench per-task scores yet — bench rank pending a published head-to-head guide; Premium pricing; Fusion premium panel reportedly out-scores it at half the API cost.
When should I pick Claude Mythos 5 over Claude Fable 5?
Pick Claude Mythos 5 for: Vetted enterprise partners with Mythos-class access; (For everyone else: read the Mythos ban coverage instead of waiting for access). The trade-off is the weaknesses we logged on the bench: No public API access — can't be benched against the open field; Restricted distribution makes it effectively unavailable to most builders.
How does Goldie Bench score Claude Fable 5 vs Claude Mythos 5?
Every demo on this page was built by Julian Goldie inside the Agent Operating System — same fixed prompt for both models, one shot, single HTML file out. Each result gets a 0–10 score on whether it ran, how close it hit the brief, and how good it looked. The highest score on each task gets gold; second gets silver; third gets bronze. See methodology for full provenance.
Related comparisons
Other head-to-heads using the same scoring system:
Claude Fable 5 vs Opus 4.8 Claude Mythos 5 vs Opus 4.8 Claude Fable 5 vs GLM-5.2 Claude Mythos 5 vs GLM-5.2 Claude Fable 5 vs Grok Claude Mythos 5 vs Grok Claude Fable 5 vs Qwen 3.7 Claude Mythos 5 vs Qwen 3.7Full model pages: Claude Fable 5 · Claude Mythos 5 · back to the leaderboard
Run this stack yourself.
Every demo on this bench was built inside the Agent Operating System — one prompt, one shot, single HTML file out. The Agent OS, the prompts, the templates, the weekly walkthroughs and 3,600+ founders shipping with it every day all live inside the AI Profit Boardroom.