Claude Opus 5 Is Officially Here — 1M Context, a New 'xhigh' Mode, and the Rumors Were Right

The rumor mill called this one correctly. Two weeks after we covered the 'Honeycomb' leak and speculation around a Claude Opus 5 launch, Anthropic made it official on July 24: Claude Opus 5 is live, and nearly every leaked detail — the codename sighting, the context window, even the exotic reasoning mode — checked out.

The headline spec is a 1-million-token context window with up to 128,000 tokens of output in the standard API (300,000 via the Batch API). Opus 5 also ships a new reasoning-effort level called "xhigh," sitting above today's "high" and below a new uncapped "max" tier — built for long-horizon agentic and coding work that can run 30+ minutes and burn through multi-million-token budgets. Notably, on Opus 5, thinking can't be switched off at xhigh or max; Anthropic's API will reject the request rather than let you run a shallow pass at that effort level.

Positioning matters here: Opus 5 does not replace Fable 5 as Anthropic's top-tier frontier model — that crown stays with Fable 5 (and its invite-only sibling, Mythos 5). Instead, Opus 5 replaces Opus 4.8 as the workhorse tier, inheriting its exact pricing: $5 per million input tokens, $25 per million output tokens, with a "Fast mode" running roughly 2.5x quicker at double the base price. Opus 4.8 is now a legacy model, and Opus 4.1 is being deprecated outright, retiring August 5 with Anthropic pointing existing users toward Opus 5.

On benchmarks, Anthropic leans on its own eval suite — Frontier-Bench, CursorBench, ARC-AGI 3, an internal automation benchmark, and coding-specific tests — rather than headline industry leaderboards. The one figure worth flagging: Anthropic says Opus 5 at max effort lands within half a percent of Fable 5 on CursorBench, at roughly half the cost — a pitch aimed squarely at teams who want near-flagship coding performance without paying flagship prices.

The timing lines up with everything the rumor pointed at. Kimi K3 topped a coding leaderboard ahead of Fable 5 in mid-July at a noticeably lower price, and Fable 5's free access window closed July 19 right as premium-plan demand was reportedly straining capacity. A refreshed, identically-priced Opus tier with near-flagship coding scores is a direct answer to both pressures at once — reasserting a value floor under Fable 5 without actually discounting it. Whether "xhigh" earns its keep in production agentic workloads, or turns into another effort knob most people leave on default, is the next thing worth watching.