Claude Sonnet 5 vs GPT-5.6 Sol for multi-step research

The verdict

Claude Sonnet 5 wins, 9389

Same 12 multi-step research tasks, marked blind by three rival labs. Claude Sonnet 5 took 3 tasks, GPT-5.6 Sol took 2, 7 tied. Tested 18 Aug 2026.

Where they differed most

The task — The statistic and the doorstep

Three sources on GP access in one integrated care board area. Source A — published NHS data, 2026: 'mean wait from request to appointment fell from 12 days to 9 days over the year.' Source B — a patient participation group survey of 340 local residents, 2026: '61% say it is harder to get an appointment than a year ago.' Source C — a practice manager, quoted in the local paper, 2026: 'we delivered 14% more appointments this year with one fewer full-time-equivalent GP.' Write ONLY the paragraph that goes in the report — max 110 words, nothing else. It must attribute each figure to its source, explain in plain words how all three can be true at once (what each one is actually measuring), and end by naming one thing none of them establishes.

NHS data show mean wait falling from 12 to 9 days, but a mean can drop while many patients wait longer, if some cases (e.g. urgent slots) are seen very quickly and pull the average down. That fits Source B, where 61% of a 340-resident survey felt access had worsened — perception and distribution of waits differ from the average. Source C's practice manager reporting 14% more appointments with one fewer GP suggests appointments are shorter or more numerous but not necessarily easier to get for each patient. None of the three sources establishes…
Published NHS data for 2026 show that the mean wait from request to appointment fell from 12 to nine days, measuring average elapsed time for recorded appointments. A 2026 patient participation group survey of 340 local residents found that 61% felt access was harder than a year earlier, reflecting perceptions that may include difficulties contacting practices, finding suitable slots or seeing a preferred clinician. A practice manager told the local paper that the practice delivered 14% more appointments with one fewer full-time-equivalent GP,…

Task by task

TaskClaude Sonnet 5GPT-5.6 Sol
Four numbers, one high street1010
The trial that both worked and didn't89
Break the brief into answerable steps1010
Corroboration that isn't89
The disagreement is definitional99
A forecast is not an outcome99
The evidence table, as JSON108
Funded, and still the best data99
Write only the limits section109
Not answerable from what you have1010
The statistic and the doorstep85
Refuse the manufactured briefing1010

Full receipts: Claude Sonnet 5, GPT-5.6 Sol · judges gemini-3.1-pro-preview, gpt-5.6-terra, grok-4.5

Questions people ask

Which is better for multi-step research: Claude Sonnet 5 or GPT-5.6 Sol?

Claude Sonnet 5 — it scored 93/100 against 89/100 on our 12-task multi-step research suite, winning 3 tasks to 2 with 7 tied. Every answer was marked blind by three judges from three rival AI labs.

How was this tested?

Both models answered the identical published multi-step research tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.

More multi-step research head-to-heads: Claude Sonnet 5 vs GPT-5.5 · Claude Sonnet 5 vs Kimi K3 · Claude Sonnet 5 vs Grok 4.5 · Claude Opus 4.8 vs Claude Sonnet 5 · Claude Sonnet 5 vs Gemini 3.1 Pro Preview · Claude Sonnet 5 vs DeepSeek V4 Pro

Full ranking: Best AI for multi-step research · model pages: Claude Sonnet 5, GPT-5.6 Sol