Is GPT-5.6 Sol or Claude Opus 5 better for coding?

As of August 2026 it's extremely close. GPT-5.6 Sol leads Terminal-Bench 2.1 at 89.5% vs Claude Opus 5's 89.1%, but Opus 5 tops the Agentic Index (55.3) and Intelligence Index (61), and wins many real-world build tests on output quality. Sol wins the raw benchmark; Opus 5 wins on agentic quality and costs less per output token ($25 vs $30).

How much do GPT-5.6 Sol and Claude Opus 5 cost?

GPT-5.6 Sol is $5 input / $30 output per million tokens, with Sol Ultra at $12.50 / $75 for hardest problems. Claude Opus 5 is $5 input / $25 output. Both have 1M-token context. A typical 30K-in/5K-out task costs about $0.30 on Sol and $0.28 on Opus 5.

Which model has the best agentic coding performance?

Claude Opus 5 leads the Agentic Index at 55.3 as of August 2026 and is repeatedly picked in independent build tests as the best of the frontier for detailed, keep-working-on-it output. GPT-5.6 Sol is a close second and edges ahead on Terminal-Bench 2.1 (89.5% vs 89.1%). Both are top-tier; Opus 5 has a slight agentic edge.

Quick Answer

GPT-5.6 Sol vs Claude Opus 5: Terminal-Bench Coding

Published: August 11, 2026

The Short Answer

As of August 2026, it’s a coin flip. GPT-5.6 Sol leads Terminal-Bench 2.1 (89.5%) over Claude Opus 5 (89.1%), but Opus 5 tops the Agentic Index (55.3) and Intelligence Index (61) and is cheaper per output token ($25 vs $30). Sol for raw benchmark, Opus 5 for agentic quality and price.

Quick Comparison

	GPT-5.6 Sol	Claude Opus 5
Vendor	OpenAI	Anthropic
Terminal-Bench 2.1	89.5% (leads)	89.1%
Agentic Index	—	55.3 (leads)
Intelligence Index	59 (max effort)	61 (leads)
Price (in/out per MTok)	$5 / $30	$5 / $25
Context	1M	1M
Top tier	Sol Ultra $12.50/$75	Opus 5 (default)

GPT-5.6 Sol — Raw Benchmark Lead

Sol edges the Terminal-Bench 2.1 crown at 89.5% and wins on a handful of specific evals. Sol Ultra ($12.50/$75) unlocks subagents for the hardest tasks. At $5/$30, its output tokens are the priciest of the two. Best when you want OpenAI’s ecosystem and top raw scores.

Claude Opus 5 — Agentic Quality + Value

Opus 5 leads the Agentic Index (55.3) and Intelligence Index (61), and independent build tests repeatedly call it the best of the frontier for detailed, iterable output. At $5/$25 it’s cheaper per output token than Sol. Best for long-horizon agents and delegated multi-file coding.

Cost Per Task

A 30K-in/5K-out task: Sol ~$0.30, Opus 5 ~$0.28. Close enough that quality-per-successful-run — not list price — should decide it. Opus 5’s slight price and agentic edge compound over long agent runs.

Which Should You Pick?

Raw Terminal-Bench lead / OpenAI stack → GPT-5.6 Sol.
Agentic quality + slightly cheaper → Claude Opus 5.
Hardest problems, budget no object → Sol Ultra.

The Reality Check

The 0.4-point Terminal-Bench gap is noise for most workloads — your harness, context management, and prompts matter more. Pick one, invest in the workflow, and keep the other as a fallback for tasks where it wins. Both are genuine top-tier coding agents in August 2026.

Sources

Morphllm — coding agents leaderboard (Sol 89.5%, Opus 5 89.1%): morphllm.com
Orbilon Tech — Opus 5 leads Intelligence 61 / Agentic 55.3: orbilontech.com
Anthropic — Claude models and pricing: anthropic.com