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NewsMaterial3 min readDisconfirmAI Editorial

Technical Author's Real-World Test: Claude Fable 5.2 Has a Lower Unit Price, but Actual Coding Task Costs Are About Three Times That of GPT-6 Astra

Although Anthropic's Claude Fable 5.2 standard API price is lower than OpenAI's GPT-6 Astra, technical author Jessica Wachtel's real-world tests on three coding tasks showed that Fable 5.2 consumed approximately five times as many tokens, making the total cost about 3.3 times that of Astra. This validates OpenAI President Greg Brockman's assertion that 'price per task is what matters.'

2026-11-14 22:00 GMT+8

When Anthropic released Claude Fable 5.2 on November 9, it set its standard API price at $8 per million uncached input tokens and $40 per million output tokens, which is lower than OpenAI's GPT-6 Astra ($10/$50). This price cut was widely promoted as a cost advantage for Fable 5.2. However, The New Stack technical author Jessica Wachtel conducted independent tests using three coding tasks and found that a lower list price does not necessarily mean lower actual spending.

Wachtel ran each model once via the respective vendor APIs with default settings to test three tasks simulating real development work: fixing 10 planted bugs in a 2,600-line billing codebase, reviewing an EU invoicing package for 45 manually planted defects, and writing validation code from scratch for VAT IDs in 27 countries and IBANs in 34 countries. Each task was scored out of 50 by an automated script.

In the bug-fixing task, both models fixed all 10 bugs and passed all 50 hidden checks, each requiring 12 conversation turns. However, the processes differed significantly: Fable 5.2 consumed over 17,000 reasoning tokens, while Astra used only 819. Fable 5.2 cost approximately $2.51 and took 326 seconds, whereas Astra cost about $0.98 and took 122 seconds. For the same score, Fable 5.2 cost about 2.6 times more than Astra.

Code review was the only task where scores differed. Fable 5.2 scored 49, while Astra scored 45. Fable 5.2 identified 44 of the 45 defects with no false positives, while Astra identified 41 and incorrectly classified one Spanish ID as valid. However, Fable 5.2 spent $6.05 and 993 seconds to achieve this, compared to Astra's $0.95 and 227 seconds. Fable 5.2's extra 4 points came at a cost exceeding six times that of Astra and four times the time.

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In the code-writing task, both models achieved a perfect score of 50, yet Fable 5.2 still cost 2.3 times as much as Astra. Across all three tasks, Fable 5.2's total cost was approximately $13.39, while Astra's was about $3.99—despite Fable 5.2's lower unit price, the total cost was roughly 3.3 times higher. Wachtel noted that Fable 5.2 consumed about five times as many tokens as Astra across these three runs.

These results corroborate OpenAI President Greg Brockman's statement at the Astra launch that price per task is key. Wachtel concluded that for such tasks, she would start with Astra, which achieved the same scores on bug fixing and code writing at about 41% of the cost; she would only consider Fable 5.2 when careful code review was needed, as it found three additional defects in that specific instance. She also acknowledged that both models missed some defects and that each model was run only once, so the four-point gap could shift in another run.

Sources

  • thenewstack.ioThe New Stack↗
  • claude.devclaude.dev Blog↗
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