Astra vs. Fable: Same Price Tag ≠ Same Bill

Astra vs. Fable: Same Price Tag ≠ Same Bill

GPT-6 Astra and Claude Fable 5.1 both have the same list price: 10 for input and 50 for output per 1 million tokens.

But that is not the same bill.

Fable 5.1 cache reads are only 0.25, while Astra’s are 1 — a 4x difference. Every time an agent loops, it may reread large chunks of system prompts, tool definitions, codebases, and historical context, and the gap keeps widening with each loop.

Astra also has a 272K billing cliff: once a single request’s input exceeds 272K, it does not just charge more for the excess portion; the entire request is repriced — input and cache fees double, and output fees increase by 50%.

In other words, in most long-context, multi-turn agent tasks, Astra is usually more expensive.