Claude Fable 5.1 vs GPT-6 Astra: tied on score, not on tokens
On the headline numbers this is a tie: the same Intelligence Index v4.3 score, the same Coding Agent Index score and the same API list price. The differences sit underneath, in how many tokens each model spent and which kinds of work each one won.
The usual choice
Pick one. Pay one subscription. Live inside one vendor's models.
- Claude Fable 5.1 with tools, Pro plan and up
- GPT-6 Astra for chat, without tool calls
- Plus 54+ models, one login
Artificial Analysis scores GPT-6 Astra and Claude Fable 5.1 identically on Intelligence Index v4.3 (53), at the same $10/$50 API price, but Astra spent about 43% as much per task. Fable 5.1 wins long-horizon knowledge work; Astra wins automation and terminal tasks. On TulexAI both cost 25 PT per 750 tokens, Pro plan and up; of the two, only Fable 5.1 takes tools.
Claude Fable 5.1 vs GPT-6 Astra vs TulexAI
| Claude Fable 5.1 | GPT-6 Astra | TulexAI | |
|---|---|---|---|
| API list price per 1M tokens (input / output) | $10 / $50 | $10 / $50 | 25 PT per 750 tokens of prompt plus reply on either |
| Intelligence Index v4.3 (Artificial Analysis) | 53 at max with fallback | 53 at max effort | Astra runs at OpenAI’s default effort |
| Coding Agent Index (Artificial Analysis) | 62 | 62 | Both on Pro ($23/mo) and up |
| Measured cost and output per index task | $7.63, ~78k output tokens | $3.26, ~27k output tokens | Billed in Platform Tokens, not per task |
| Long-horizon knowledge work (AA-Briefcase / GDPval-AA v2 Elo) | 1662 / 1764 | 1562 / 1580 | Fable 5.1 built in |
| Automation and terminal work (AutomationBench-AA / Terminal-Bench v4.0) | 59% / 52% | 68% / 59% | Astra built in, without tool calls |
| Science and hard reasoning (SciCode / Humanity’s Last Exam) | 63% / 59% | 56% / 55% | Fable 5.1 built in |
| Output speed and time to first token (measured) | 65 tok/s, 213s | 58.1 tok/s, 334s at max effort | Not measured on TulexAI |
| Tool use and function calling | Supported on TulexAI | Responses API only, not Chat Completions | Fable 5.1 takes tools; Astra tool requests are refused |
| Consumer plan access | Claude Pro $20/mo, reduced share of weekly limits | ChatGPT Plus $20/mo in Work and Codex; Chat on Pro, Business, Enterprise | Both in one chat, Pro ($23/mo) and up |
Which should you pick?
Pick Claude Fable 5.1 when the job is long-horizon knowledge work, science code or anything that needs tools: Artificial Analysis measured it 100 Elo ahead on AA-Briefcase and 184 ahead on GDPval-AA v2, it won SciCode and Humanity’s Last Exam, and it is the one of the two that can call functions on TulexAI. Pick GPT-6 Astra when you pay an API by the token for automation or terminal work: it matched Fable 5.1’s 53 for $3.26 a task against $7.63, and won AutomationBench-AA and Terminal-Bench v4.0. Those runs used max effort, while TulexAI serves Astra at OpenAI’s default effort, so read the scores as measured rather than promised. On our Pro plan and up both cost 25 PT per 750 tokens of prompt plus reply and sit in one chat, so the practical split is Fable 5.1 for tool work and Astra for everything that does not need a tool.
Why choose at all? TulexAI includes both
54+ models in one subscription - here are the ones that cover what Claude Fable 5.1 and GPT-6 Astra each do best.
Text & Chat
- Claude Fable 5.1Premium
- OpenAI GPT-6 AstraPremium
- Claude Fable 5Premium
Frequently asked questions
Neither, on the headline measure. Artificial Analysis scores both at 53 on Intelligence Index v4.3 (Astra at max effort, Fable 5.1 at max with fallback) and both at 62 on its Coding Agent Index. They split the sub-tests: Fable 5.1 wins knowledge work, SciCode and Humanity’s Last Exam, while Astra wins AutomationBench-AA and Terminal-Bench v4.0.
That 66 comes from Artificial Analysis’s 2026-09-01 launch write-up, on the index as it stood before version 4.3. Version 4.3, published 2026-09-07, added harder agentic tests, and on it Fable 5.1 scores 53. The two figures sit on different scales, so neither should be compared with the other.
The API list price is identical at $10 input and $50 output per 1M tokens. Spend per task is not: running the full Intelligence Index cost Artificial Analysis $5,324 on Astra (60M tokens) against $13,129 on Fable 5.1 (188M). Caching differs too, with Astra at $1 per 1M cached input and Fable 5.1 at $0.25 per 1M cache reads.
No. OpenAI supports function calling, web search, file search, code interpreter and computer use for Astra only on its Responses API. TulexAI uses Chat Completions, so a tool request sent to Astra is refused with a clear error. Claude Fable 5.1 does take tools on TulexAI.
Pro at $23/month and up, including VIP and Elite; Basic carries neither. Each costs 25 PT per 750 tokens of prompt plus reply from a frontier text allowance shared with Claude Fable 5, and Astra replies are capped at 8,192 output tokens.
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