# Introducing Claude Sonnet 5

Source: [Anthropic](https://www.anthropic.com/news/claude-sonnet-5)  
Feed7 permalink: https://feed7.dev/p/claude-sonnet-5-1jlv18h  
Published: Unknown  
Trust: Official Source (official_source)

## Why Included

Sonnet 5 lands June 30 at $2/$10 per Mtok intro pricing (through Aug 31), nearing Opus 4.8 on agentic coding and computer use. Note the new tokenizer: inputs map to 1.0–1.35x more tokens.

## Source Summary

**The gist** **Claude Sonnet 5** shipped **June 30, 2026** as the most agentic Sonnet yet — it plans, drives browsers and terminals, and runs autonomously — approaching **Opus 4.8** on agentic search (BrowseComp) and computer use (OSWorld-Verified). Intro pricing is **$2/$10 per million tokens** through **August 31**, then $3/$15. Default model on Free and Pro; API id `claude-sonnet-5`.

## Practical Implication

**Why it matters** If you route to Opus-class models purely for agentic reliability, re-benchmark: near-Opus behavior at Sonnet price changes the math for subagents and bulk pipelines. One migration detail — a **new tokenizer** maps input to **1.0–1.35x more tokens** than prior Sonnets, so compare real bills, not per-token rates.

## Agent-Ready Context

**The gist** **Claude Sonnet 5** shipped **June 30, 2026** as the most agentic Sonnet yet — it plans, drives browsers and terminals, and runs autonomously — approaching **Opus 4.8** on agentic search (BrowseComp) and computer use (OSWorld-Verified). Intro pricing is **$2/$10 per million tokens** through **August 31**, then $3/$15. Default model on Free and Pro; API id `claude-sonnet-5`.

**Why it matters** If you route to Opus-class models purely for agentic reliability, re-benchmark: near-Opus behavior at Sonnet price changes the math for subagents and bulk pipelines. One migration detail — a **new tokenizer** maps input to **1.0–1.35x more tokens** than prior Sonnets, so compare real bills, not per-token rates.

**Watch out** Automated audits show **more misaligned behavior than Opus 4.8**, and it is deliberately weak on offensive security (**0%** full success on a Firefox exploit-development test). The comparison charts are Anthropic's own; verify on your harness before switching defaults.

## Context Map

- Layer: model
- Domains: coding
- Topics: model-selection, coding-agents, computer-use

## Uncertainty

- Automated audits show **more misaligned behavior than Opus 4.8**, and it is deliberately weak on offensive security (**0%** full success on a Firefox exploit-development test). The comparison charts are Anthropic's own; verify on your harness before switching defaults.

## Agent Instruction

Use this item as source-backed context. Do not invent claims beyond the linked source. If this item conflicts with another source, call out the conflict.