#reasoning-effort

Choose a frontier AI model by workload, API price, context, effort and access, with current vendor evidence, explicit cost assumptions and dated comparisons.

Anthropic's charts give 40 score and cost points for Sonnet 5.5 and Opus 5.5. Up to $2 a task Sonnet wins three of four; at $5, Opus wins all four.

Rung names, counts, defaults and whether reasoning can be switched off, across 18 coding-CLI and model-API surfaces, gaps and unresolved cells included.

Every vendor names its reasoning-effort settings differently and the rungs do not line up. What the ladders look like, and where thinking cannot be disabled.

xAI's Grok 4.6 keeps Grok 4.5's headline rates, but the $2/$6 tier only holds below a 200K-token prompt: cross it and the whole request reprices.

xAI's launch table sets Grok 4.6's default effort against GPT-5.6 Sol's and Fable 5's documented ceilings. Why the rung changes what a score means.

ChatGPT's effort slider moves a developer-API control into the chat window; a Think button is announced next week. What effort changes, how vendors label it.

K3's least-used surfaces are its 1M context, native vision and reasoning-effort dial. Switching effort mid-session forfeits the cache rate that funds it.

Kimi K3 leads GPT-5.6 Sol on seven of fourteen vendor-reported benchmarks, but Sol's effort controls and ultra mode reframe agentic fit beyond raw scores.

Migrate GPT-5.2 to 5.5 — reasoning-effort behavior change, tool-call schema diff, cost-curve impact, structured outputs, and a phased rollout plan.

Independent latency data read Nov 5, 2026: time to first answer token by endpoint, reasoning effort and speed tier, with vendor claims labelled separately.