Claude Fable 5 (released June 9, 2026) has significantly different optimal prompting patterns compared to Opus 4.8, especially for long-horizon autonomous tasks.
Current prompt-master is optimized for Claude 4.x and does not yet account for the new recommendations from the official guide:
https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5
What needs to be adapted:
Add a dedicated Tool Profile for Claude Fable 5 (and Claude Code on Fable 5)
Update routing logic in SKILL.md
Create/adapt a prompt template that follows Fable 5 best practices:
Minimal scaffolding
"Act when ready" behavior
Proper use of effort levels
File-based memory recommendations
send_to_user tool usage for long runs
Progress auditing and reduced overplanning
Brevity guidelines for final output
Review and update patterns.md (some current anti-patterns may no longer apply)
Add relevant examples
This will allow prompt-master to generate high-quality prompts specifically optimized for the new model.
Claude Fable 5 (released June 9, 2026) has significantly different optimal prompting patterns compared to Opus 4.8, especially for long-horizon autonomous tasks.
Current prompt-master is optimized for Claude 4.x and does not yet account for the new recommendations from the official guide:
https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5
What needs to be adapted:
Add a dedicated Tool Profile for Claude Fable 5 (and Claude Code on Fable 5)
Update routing logic in SKILL.md
Create/adapt a prompt template that follows Fable 5 best practices:
Minimal scaffolding
"Act when ready" behavior
Proper use of effort levels
File-based memory recommendations
send_to_user tool usage for long runs
Progress auditing and reduced overplanning
Brevity guidelines for final output
Review and update patterns.md (some current anti-patterns may no longer apply)
Add relevant examples
This will allow prompt-master to generate high-quality prompts specifically optimized for the new model.