Claude Opus 5.5 vs GPT‑6 Astra: Who Wins on Coding Agents and Cost Update

Early September felt like “Astra or nothing.” Then Anthropic dropped Claude Opus 5.5 and quietly changed the conversation. On paper, Astra is still the flagship. But on the benchmarks that matter most for coding agents and on the bill you actually pay Opus 5.5 suddenly looks like the smarter default for many teams.

Coding agents: where Opus 5.5 edges ahead

On Terminal‑Bench 4.0, which simulates long, multi‑step coding and terminal workflows:

• Claude Opus 5.5: 66.4%
• GPT‑6 Astra: 57.9%

On FrontierCode v1.1, another tough coding benchmark, Opus 5.5 again sits slightly ahead (54.4% vs 53.3%). If your agents spend most of their time in repos, terminals and CI pipelines, those gaps are meaningful.

Astra still leads on some hard reasoning and science tests, but for pure “can it code and operate tools reliably,” Opus 5.5 is punching above its weight class.

Cost per task: the real battleground

Here’s where the story flips. Astra’s API pricing is $10 / $50 per million tokens. Opus 5.5 is $4 / $20. When you add in better caching and fewer tokens per task, independent analyses show Opus 5.5 can be ~60% cheaper per task than Astra on typical agent workloads.

For a team running hundreds or thousands of agent tasks a day, that’s not a nice‑to‑have. It’s the difference between “we can scale this” and “we need to throttle.”

So who wins?

If your priority is maximum reasoning power for research, science or top‑end strategy, Astra still has the edge. But if your core use case is coding agents, workflow automation and professional knowledge work, Opus 5.5 gives you equal or better performance on the relevant benchmarks at a much lower cost.

In a lot of enterprise stacks, GPT 6 Astra becomes the “specialist” model, and Opus 5.5 becomes the everyday engine for most agent tasks.