Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual...
Model details →Anthropic: Claude Fable 5.1 (batch) vs OpenAI: GPT-6 Astra Pro
Anthropic: Claude Fable 5.1 (batch) wins on 2 of 6 axes — pricing and capability skew in its favour for most workloads.
GPT-6 Astra Pro is the same underlying model as [GPT-6 Astra](https://openrouter.ai/openai/gpt-6-astra), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://develope…
Model details →Side-by-side comparison
| Capability | Anthropic: Claude Fable 5.1 (batch) | OpenAI: GPT-6 Astra Pro | Winner |
|---|---|---|---|
| Context window Maximum number of input tokens the model can attend to in a single request. | 1M | 1.1M | 🏆 OpenAI: GPT-6 Astra Pro |
| Input price (per 1M) Cost per million input tokens billed by the provider. | $5.00 | $10.00 | 🏆 Anthropic: Claude Fable 5.1 (batch) |
| Output price (per 1M) Cost per million output tokens billed by the provider. | $25.00 | $50.00 | 🏆 Anthropic: Claude Fable 5.1 (batch) |
| Tool / function calling First-class support for emitting structured tool calls. | Yes | Yes | Tie |
| Vision input Accepts image inputs alongside text. | Yes | Yes | Tie |
| Reasoning mode Internal chain-of-thought / extended-thinking support. | Yes | Yes | Tie |
Frequently asked questions
Is Anthropic: Claude Fable 5.1 (batch) better than OpenAI: GPT-6 Astra Pro?
Anthropic: Claude Fable 5.1 (batch) wins on 2 of 6 axes — pricing and capability skew in its favour for most workloads.
What's the price difference between Anthropic: Claude Fable 5.1 (batch) and OpenAI: GPT-6 Astra Pro?
Input: $5.00 vs $10.00 per 1M tokens. Output: $25.00 vs $50.00 per 1M tokens.
What context windows do Anthropic: Claude Fable 5.1 (batch) and OpenAI: GPT-6 Astra Pro support?
Anthropic: Claude Fable 5.1 (batch) supports up to 1M tokens. OpenAI: GPT-6 Astra Pro supports up to 1.1M tokens.
Do both Anthropic: Claude Fable 5.1 (batch) and OpenAI: GPT-6 Astra Pro support tool calling?
Anthropic: Claude Fable 5.1 (batch): yes. OpenAI: GPT-6 Astra Pro: yes.