Anthropic launches Claude Sonnet 5, a cheaper model that matches Opus on agentic tasks

Anthropic launched Claude Sonnet 5 on Tuesday, positioning it as its most capable midsize model and a cost-effective alternative to the top-tier Opus 4.8 for developers building AI agents.

The new model is built around agentic performance — it can make plans, use tools like web browsers and code terminals, verify its own outputs, and complete long multi-step tasks with minimal human check-ins. Anthropic says Sonnet 5 achieves capabilities "that, just a few months ago, required larger and more expensive models."

Benchmark Performance

On agentic coding benchmarks, Sonnet 5 scores 63.2%, compared to Opus 4.8's 69.2%. On knowledge-work tasks, Sonnet 5 actually edges out Opus 4.8. The gap has narrowed considerably — the key question for enterprise developers is now whether that remaining difference justifies paying the higher price for Opus.

Pricing

Until August 31, 2026, Sonnet 5 is priced at $2 per million input tokens and $10 per million output tokens. After that, prices rise to $3 and $15 respectively. Both tiers are substantially cheaper than Opus 4.8, GPT-5.5, and Gemini 3.1 Pro — making Sonnet 5 an attractive option for high-volume agentic workloads where cost scaling matters.

Safety Improvements

Anthropic also reports that Sonnet 5 shows lower hallucination rates, improved refusal of malicious requests, and generally better behavior compared to Sonnet 4.6. These safety improvements matter more as agents operate autonomously over longer task sequences, where a single error can cascade.

What This Signals

The release confirms a broader trend: agentic capability is no longer a premium feature. The competitive battleground has shifted from "can this model use tools?" to "how reliably and cheaply can it complete full workflows without intervention?" Sonnet 5 draws the line squarely in that space — able to handle most enterprise agent workloads at a fraction of the cost of frontier models.

As first reported by TechCrunch, Claude Sonnet 5 is available immediately via the Anthropic API.