Is my AI assistant smarter? How to properly use Claude Opus 5 and Fable 5

Imagine this: your daily AI assistant has suddenly upgraded to ‘supercomputer’ level intelligence. But when you give it commands as usual, it doesn’t respond as smartly as before. Why does this happen?

Anthropic’s recently introduced AI models, Claude Opus 5 and Fable 5, are exactly that case. The ‘guidelines’ you painstakingly set for your assistant differ slightly from the way the new models think. It is similar to asking a highly intelligent student to continue solving ‘kindergarten-level worksheets.’

Why is an update necessary?

The advancement of AI technology is not just a process of increasing intelligence metrics. While you used to have to give AI very specific, step-by-step instructions, the latest models have much more powerful capabilities for independent thinking and self-verification. Claude Fable 5 is particularly specialized in executing complex and long-form projects, providing an amazing experience that feels like collaborating with a veteran researcher (Claude Fable 5).

However, the configuration files (CLAUDE.md) or custom skills we wrote for previous models may not be fully compatible with the way the new models operate (Source: Ask HN). In other words, if you leave your settings as they are, your assistant will not be able to reach its 100% potential, trapped by outdated guidelines.

Simple analogy: Taming a ‘high-level assistant’

Think of an AI model’s configuration file as an ‘operational manual for your assistant.’ If your existing manual was designed for ‘simple errands,’ the new manual needs to be updated to enable ‘strategic decision-making.’

• As an analogy: It is like giving a team leader the same orientation manual you gave a junior employee 10 years ago. A team leader wants to see the big picture and make their own judgments, so it would be inefficient if the manual only contained detailed instructions like “here is how to make coffee.”
• Configuration optimization: Anthropic recommends revising guidelines to leverage the new models’ features, such as response length control and the ability to break down tasks autonomously (Source: Prompting Claude Opus 5).

Current situation: How to start?

The first thing to do is get help from an expert. If you are using Claude Code, try typing the /doctor command. This command verifies that your system is properly set up for the new model environment and automatically cleans up your skills and CLAUDE.md file to align with the latest environment (Source: The new rules of context engineering).

1. Update settings: You need to simplify and optimize your existing CLAUDE.md and skill files to meet the requirements of the latest models (Source: Anthropic Releases Claude Opus 5).
2. Model selection: In your new Claude Code session, select the model and optimize performance by adjusting the ‘effort’ level based on the complexity of the task (Source: Claude code update).

What will happen in the future?

Models like Claude Fable 5 will evolve to understand massive contexts of up to 1 million tokens (the unit of information an AI can remember at once — equivalent to dozens of books), and will progress to the level of writing and verifying code on their own (Source: Fable5AI). We are entering an era that goes beyond simple coding, where you design your ideas with an AI assistant and solve complex errors together. Now, all you need to do is update the ‘manual’ for this powerful assistant to the latest version.

MindTickleBytes AI Reporter’s View

Technology always runs faster than we think. More important than changing tools is changing the way we ‘ask questions’ when dealing with them. Wake up your AI with the latest settings and solve bigger problems.

References

1. Ask HN: How to rewrite Claude.md and install the skill for Opus5 and Fable5
2. GitHub - DizzyMii/fable-skills: Six Claude Code skills
3. The new rules of context engineering for Claude 5 generation models
4. Prompting Claude Opus 5 - Claude Platform Docs
5. Claude Opus 5 in Claude Code: A 2026 Guide - codersera.com
6. Claude code update — Using Claude Opus 5 in Claude Code
7. Writing Opus 5 / Fable 5 Prompts - GitHub
8. claude-skills/fable-mode/SKILL.md
9. GitHub - samirinyemi/fable5-skill-library

10. [Hacker News

    Ask HN](https://nilaykhandelwal.com/item/49080135)

11. Claude Opus 5 Is Powerful. Your Setup Decides How Powerful
12. Karpathy’s CLAUDE.md Skills File: The Complete Guide
13. Migration guide - Claude Platform Docs
14. Claude

15. [Claude Fable

    Anthropic](https://www.anthropic.com/claude/fable)

16. Fable5AI — Independent Model Guide & Prompt Workspace
17. Claude Opus 5 review: great at coding (but I hate talking to it)
18. GitHub - alirezarezvani/claude-skills
19. Claude Fable 5 · Free AI Chatbot
20. Anthropic Releases Claude Opus 5 at Half the Token Price of Claude Fable 5 - gHacks TechNews