Claude

Claude Sonnet 5.5 (Sept 28, 2026): $2/$10 per 1M tokens, 1M context, 128K output, API ID claude-sonnet-5-5. Benchmarks vs Opus 5.5 and GPT-6 Sol, Python quickstart, and the five breaking changes from Sonnet 5.

Claude Opus 5.5 and GPT-6 Sol launched 90 minutes apart on 22 Sept 2026. Opus 5.5 wins on benchmarks; Sol costs half per token. Pricing, cost per task, shared benchmarks, Claude Code vs Codex, and which to pick.

Migrating from Claude Opus 5 to Opus 5.5: thinking can't be disabled, forced tool_choice returns 400, thinking blocks are bound to the conversation, computer_20251124 is rejected, and effort defaults to medium. Exact errors, before/after code, costs, and a rollback plan.

Claude Opus 5.5 launched 22 September 2026: model IDs on every platform, 1M context, $4/$20 pricing vs Opus 5 and Fable 5.1, the new medium effort default, full benchmark table, Artificial Analysis ranking and its token-usage catch, and system-card safety notes.

GPT-6 Astra lists at exactly twice Claude Opus 5. On the one independent same-harness index that has run both, Opus 5 scores higher. Here is the full cost and benchmark breakdown.

GPT-6 Astra and Claude Fable 5.1 launched two days apart at identical $10/$50 pricing. We check the verified benchmarks and run the real cost arithmetic on caching and long context.

Fable 5.1 leads every head-to-head benchmark but costs 2x on list. Its cache reads are half Opus 5's, which flips the cost answer for cache-heavy agentic workloads.

Claude Fable 5.1 ships at the same $10/$50 price as Fable 5 — but cache reads drop 4x to $0.25/MTok, agentic benchmarks jump sharply, and forced tool_choice now returns a 400 error. A full head-to-head with the caching arithmetic and a clear switch/don't-switch rule.

Anthropic released Claude Fable 5.1 on 1 September 2026 at the same $10/$50 price as Fable 5. The real change is a 4x cut to cache reads, plus a breaking change to forced tool use.

Claude Opus 5 leads on independently verified coding benchmarks; Kimi K3 costs 40% less and ships open weights. A head-to-head on benchmarks, cost, context, openness and speed — with an explicit decision rule.

Meta published a benchmark chart where its own model loses to Claude Opus 5 — and independent harnesses rank Muse Spark 1.2 lower still. A close read of the launch numbers.

Claude Opus 5 launched at the same price as Opus 4.8 but posts a full generation of gains: 79.2% on SWE-bench Pro, double the agentic coding, a new effort toggle, and stronger safety. Here's what changed and why the upgrade is low-risk.

Claude Opus 5 landed July 24, 2026 as Anthropic's near-frontier default. A task-by-task guide to choosing between Sonnet 5 and Opus 5 by workload and budget, with real benchmarks, pricing, and a which-to-pick decision list.

Claude Opus 5 comes close to Fable 5's frontier intelligence at half the input price ($5 vs $10). Here's the benchmark head-to-head, the pricing breakdown, and exactly when Fable 5 is still the right call for long-horizon autonomous agents.

A hands-on guide to running Claude Opus 5 in Claude Code: how to select claude-opus-5, when to use fast mode, how effort levels work, self-verification in agent loops, and the 1M context for large repos.

A complete benchmark reference for Claude Opus 5: what Frontier-Bench, ARC-AGI-3, GDPval-AA v2, SWE-bench Pro, CursorBench, AutomationBench and OSWorld measure, Opus 5's exact score on each, the comparison models, and why capability per dollar is the real story.

Claude Opus 5 lands at $5 input / $25 output per million tokens, same as Opus 4.8 and half of Fable 5. The real cost lever is the new low/medium/high effort toggle. Here's a full pricing table, a worked cost example, and a routing strategy that can cut your AI bill ~40%.

Claude Opus 5 vs GPT-5.6 Sol, head-to-head on the public numbers: Frontier-Bench 43.3 vs 34.4, ARC-AGI-3 30.2 vs 7.8, GDPval-AA v2 1,861 vs 1,736. Benchmarks, pricing, and the honest switching-cost caveat.

Anthropic's Claude Opus 5 brings near-frontier intelligence at half the price, a low/medium/high effort toggle, and record coding benchmarks. Here's the full breakdown.

Fable 5's included-in-subscription window ends July 7, 2026. Here's exactly how usage credits work, what Fable 5 costs after the switch, and how to set spend limits so an agent doesn't drain your balance.

Anthropic's agentic mid-tier Claude Sonnet 5 vs OpenAI's flagship GPT-5.5: benchmarks, pricing, and when to use which for agents and reasoning.

Claude Sonnet 5 is the agentic mid-tier workhorse; Opus 4.8 is Anthropic's reasoning flagship. When to use which by workload, cost, and speed.

Anthropic's most agentic Sonnet yet, launched June 30, 2026. Full benchmark table, real pricing (including the tokenizer catch), availability, and honest verdicts vs Sonnet 4.6, Opus 4.8, GPT-5.5 and Gemini.

Claude Fable 5 is back online as of July 1, 2026, after the U.S. lifted its export-control order. Here's what changed, how Anthropic brought it back, and how to access it.