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AI Agents

Claude Opus 5.5 Complete Guide: Model Specifications, API Notes, and Claude Code Operations

A complete guide to Claude Opus 5.5: prices 20% below Opus 5 with 60% cheaper cache reads, API migration notes such as the medium default effort and thinking that can no longer be disabled, and the new default model and Fast mode in Claude Code.

ClaudeCode

The Complete Guide to Claude Fable 5 — Model Specs and Claude Code Operations from the Official Docs

Hello! Claude Fable 5, which arrived in June 2026, has had an eventful first month: a suspension under export controls right after release, a global re-rollout, and then its departure from the subscription allowance. This blog has followed the situation at each turn. For the overall picture, see Finally Generally

ClaudeCode

What's Next for Claude Fable 5? A Fact-Based Look at the Timeline, Costs, and Outlook

Hello! On July 2, 2026 (Japan time), Claude Fable 5 became available again from Japan. Anthropic's top-tier model "Claude Fable 5" arrived in June 2026 to enormous attention, was suspended just three days later by a U.S. government directive, and then returned on July 1

ClaudeCode

What Is That "court" in Claude Code? The "XML Leak" Phenomenon and Guarding Against Unexecuted Tool Calls

Hello! This is the Qualiteg Product Development Team. When you use Claude Code, the raw tool-call XML (<invoke> or <parameter>) sometimes appears verbatim on screen, or the assistant reports "done" even though no command actually ran and no PR was actually created — and things

ClaudeCode

The Complete Guide to Claude Opus 4.8 — Model Specs and Claude Code Best Practices from the Official Docs

Hello! In May 2026, Anthropic released Claude Opus 4.8. Then, in June 2026, Fable5 /Mythos5 was released. However, owing to certain circumstances, it is currently (as of June 18, 2026) unavailable — which makes Claude Opus 4.8 effectively the highest-tier Claude model available to the general public. So this

ClaudeCode

The AI "Detected," "Refused," and "Apologized for" an Attack That Never Came — Our Experience with Fable 5 on Claude Code

A record of AI "confabulation" across a model switch, traced through raw Claude Code logs Hello! This is the Qualiteg Product Development Team. Today's story is about a question: how far can we trust an AI agent's reports ? It began in one of our

Generative AI Frontlines

Suspended Three Days After Release: What the U.S. Government Directive on Fable 5 / Mythos 5 Reveals About a New AI Availability Risk

Hello! In our previous article, we covered Claude Fable 5 and Claude Mythos 5, announced by Anthropic on June 9, 2026. Fable 5 took Mythos-class capability, added safeguards, and brought it down into a form that could be offered to general users. We described it as "the myth descending

LLM

Finally Generally Available: A Practitioner's Read on Claude Mythos 5 / Fable 5

Hello! This is the Qualiteg Product Development Team. On June 9, 2026, Anthropic announced Claude Fable 5 and Claude Mythos 5. In this article, we sort out what Fable 5 is, how it differs from Mythos 5, and what changes from the standpoint of using Claude Code and AI agents

ClaudeCode

Why Legitimate Operations Work Becomes a "Usage Policy Violation" in Claude Code — Real-Time Cyber-Safeguard False Positives and How to Handle Them

Hello! Today we take a detailed look at the "Usage Policy violation" errors that can suddenly appear while using Claude Code — namely, the real-time cyber safeguards and their false positives (misdetections) — covering both their patterns and how to handle them. Have you ever been stopped in your tracks

ClaudeCode

Diagnosing and Fixing the Recurring "The model's tool call could not be parsed" Error in Claude Code

Hello! This is the Qualiteg Product Development Team. While developing with Claude Code (CLI), we ran into a phenomenon where the following error appeared repeatedly and brought work to a halt. ● The model's tool call could not be parsed (retry also failed). Retrying did not fix it, and

ClaudeCode

The State and Future of Coding Agents, Part 3: From AI That Writes to AI You Command — What's Changing in Development in 2026

Hello! The coding agent series has finally reached its finale! As 2026 unfolds, Claude Code, Cursor 3, and GitHub Copilot Coding Agent have all evolved beyond simple code completion or chat-style assistance into development workflows built on multiple agents. In this article we survey the latest developments in AI coding