Claude Opus 5 vs GPT-5.6 Sol
A half-point war
On Artificial Analysis's Terminal-Bench 2.1, Sol scores 89.5 to Opus 5's 89.1 — the gap between the two default agent models is down to half a point. The choice is decided off the leaderboard.
Key points
TB 2.1 gap (AA terms)
Sol 89.5 vs Opus 5 89.1 (Artificial Analysis, xhigh effort). The official tbench.ai board uses different terms — see below.
Opus 5 per million tokens (input/output)
QCode catalog price. Sol is $5/$30 — same input price, 20% more on output.
Context windows
Opus 5: 1M tokens; Sol: 400K. Opus wins long-context scenarios.
Who wins depends on the board
Sol leads by 0.4 on AA; the official tbench.ai leader is Claude Code × Fable 5 (83.8) — neither of these two tops that board.
Where each model sits
Opus 5 (07-24) is Anthropic's current flagship, Claude Code's default high-end model, with 1M context, strongest at long-horizon agent tasks and tool use. GPT-5.6 Sol is the flagship tier of OpenAI's 5.6 series (above Terra/Luna), with 400K context, and a 2.5x-speed Fast mode added 07-30 (at 2x price). They are the default high-end models of Claude Code and Codex respectively.
What a half-point gap means
Since 08-08 the Artificial Analysis figures 'Sol 89.5 vs Opus 5 89.1' have been widely quoted, and BuildApps headlined it as 'the gap is so small the benchmark is no longer the decision basis.' The industry consensus: the top two are effectively tied at agentic coding, and the decision variables have moved to context length, price, ecosystem and quota. Note there is also the official tbench.ai board (agent+model combos) — a different scoring system.
Timeline
Claude Opus 5 launches, with two betas the same day (including mid-conversation tool changes).
GPT-5.6 series repricing: Luna -80%, Terra -20%; Sol's price unchanged but gains Fast mode.
AA's 'Sol 89.5 vs Opus 5 89.1' spreads widely; 'benchmark saturation' becomes the topic.
Confirmed vs watch out
Confirmed
Both models' context windows, pricing and leaderboard gaps are backed by official pages or re-checkable leaderboards. Both have real call volume on QCode (30-day usage > 0).
Watch out
Don't compare scores across different boards: AA (direct model tests, xhigh) and the official tbench.ai (agent+model combos) are two different systems. When comparing Opus 5 and Sol, fix one leaderboard first.
Pick by scenario
Pick Opus 5
Ultra-long context (1M), the Claude Code ecosystem, long-horizon agent tasks. Output is $25 per million — $5 cheaper than Sol.
Pick GPT-5.6 Sol
The Codex ecosystem, Fast mode (2.5x speed), or an existing OpenAI toolchain. Output is $30 per million.
How to reach your own verdict
Take 5-10 real tasks from your own repo, run both models with the same agent and the same effort tier, and compare 'first-pass rate × token cost.' Two models half a point apart on a leaderboard can be a full tier apart on your workload — you only learn the direction by running them.
On QCode
Both claude-opus-5 and gpt-5.6-sol are on sale (with real calls in the last 30 days). Same key, same endpoint — switching models is changing one id, so A/B testing costs two rounds of tokens.
FAQ
Which is stronger, Opus 5 or GPT-5.6 Sol?
On AA's Terminal-Bench 2.1 it's Sol 89.5 vs Opus 5 89.1 — a 0.4 gap, effectively tied at the benchmark level. The differences are ecosystem, context and price.
How big is the price gap?
QCode catalog: Opus 5 at $5/$25, Sol at $5/$30 (per million tokens input/output). Same input price; Sol's output costs 20% more.
Who has the bigger context?
Opus 5: 1M tokens. Sol: 400K. Opus wins for huge repos and long sessions.
Why do some boards rank Opus 5 higher?
Different systems: the official tbench.ai board tests agent+model combos, vals.ai re-tests with a unified harness, and AA tests models directly. Cross-board score comparison is meaningless.
Can both be used with Claude Code / Codex?
Claude Code defaults to Claude models, Codex to OpenAI models; tools with custom endpoints (like Cline) let you pair freely.
Can I call both on QCode?
Both are on sale, switchable with the same key. Run each on real tasks once before picking your default.
Sources
Artificial Analysis (via BuildApps 08-08 and The Batch 08-21), the official tbench.ai board (scraped 08-22), Anthropic's official announcement (07-24), OpenAI's repricing announcement (07-30), QCode /models (08-22).
One key, run both
Opus 5 and Sol are both on sale on QCode at one endpoint — your own tests beat leaderboards.
Related reading
Claude Opus 5 guide
The flagship's full calling manual.
GPT-5.6 Sol Fast mode
The 2.5x Fast mode in detail.
Terminal-Bench 2.1 explained
Which board the 0.4 gap comes from.
Not affiliated with Anthropic / OpenAI. Leaderboard numbers are a 2026-08 snapshot.