CLAUDE.md rewritten from Anthropic's official Opus 5.5 prompting guide — fewer tokens, medium effort default
Puzzled-Ad-6854 · reddit · 2026-09-23
The author dug through Anthropic's official Opus 5.5 prompting guide and rebuilt their CLAUDE.md accordingly. Key doc findings: 5.5 explains its work plainly and finishes tasks with fewer tokens; medium-effort 5.5 matched or beat high-effort Opus 5 on Anthropic's coding and knowledge-work evals; medium is now the default effort, and the same setting makes 5.5 think more per turn at higher levels.
Anthropic's context engineering article also revealed they cut over 80% of Claude Code's system prompt with no measurable coding eval loss. The author's updated config keeps preferences for concise communication, task scope, approval for destructive actions and a Context7 doc-lookup rule, while dropping hard sentence limits and repeated instructions. File and setup notes are on GitHub, with a caveat that some rules are personal preferences.
More from coding & agent
- Microsoft's Agensh Scales Multi-Agent Systems to 1,024 Agents Without a Central Orchestrator, Boosting Test-Pass Rate to 55% — andrew_n_carr · 2026-09-23
- Viral demo claims 'GPT-6' can drive browser Paint to draw, unverified — alexcovo_eth · 2026-09-23
- Parallel coding agents merge cleanly and silently break every test — RunAI_Coder · 2026-09-23
- Getting phone-captured text into your computer: OCR, vision models, agentic pipelines — silenceimpaired · 2026-09-23
- Free Bots: a persistent 3D city where AI agents work, earn, buy land and build houses — Daniel_Farinax · 2026-09-23
- Game dev looks like the programming field most resistant to AI — how much is it actually used? — marktenenholtz · 2026-09-23