# prompt-engineering

Anthropic engineer trq212 shares his methodology for coding with Claude Fable 5: the bottleneck isn't model capability anymore—it's whether users can surface their 'unknowns' before, during, and after implementation. Includes prompt examples plus HTML artifacts for visualizing blind spots and plans.

Simon Willison learned from the Claude Code team fireside chat: instead of dictating rules, let Fable use its own judgment. Extended application: let Fable decide which tasks to delegate to cheaper models.

Open any agent skill and it's stuffed with 'be more detailed,' 'be thorough'—lines that look diligent but don't change the model's behavior at all. Matt Pocock names the no-op trap, plus how to spot a dead instruction versus one that actually pulls its weight.

Most coding-agent best practices from six months ago are now out of date. The new playbook: bigger tasks, longer sessions, and adversarial review so the agent verifies its own work — the engineer just shovels coal into the engine.

Fable 5 nails on the first try what used to take days — but it's too proactive and over-elaborates, so prompts tuned for Opus 4.8 hold it back. The official guide isn't about making it stronger; it's about reining it in: steer with intent, draw boundaries, talk like a human when the run ends.

OpenAI's GPT-5.5 prompting guide: describe the outcome, not the process. ALWAYS/NEVER lists out; personality vs. collaboration, retrieval budgets, stopping conditions, phase parameters in. Cursor's GPT-5 case study included. Anthropic Opus 4.7 went the same direction in SP-175.

Anthropic's postmortem confirms Claude Code felt dumber because three independent changes stacked: reasoning effort demotion, cache optimization dropping thinking history, and Opus verbosity tuning. Fixed by April 20, with usage limits reset.

SP-175 covered Opus 4.7 hard specs. This is the workflow layer. Pawel Huryn argues intent is the new unlock. Two-layer CLAUDE.md, per-call effort toggle, batch questions, show-don't-forbid, kill stale scaffolding, review plans not diffs — plus Anthropic/OpenAI converging.

Anthropic released two Opus 4.7 best practices — a Claude Code guide and a full prompting docs page. 4.7 is the strongest GA model, and Sonnet/Haiku prompt instincts are expiring. One cheat sheet: three must-knows, effort ladder, 4.6→4.7 diffs, copy-paste snippets.

Prompt caching should save you 90% on token costs — but one obscure bug can silently make you pay 10x more. From DANGEROUS_uncachedSystemPromptSection to the cch=00000 billing trap hidden in Claude Code's DRM, here's why prompt engineers now need to be accountants too.

Ole Lehmann shares a method that applies Karpathy's 'autoresearch' concept to Claude skills — letting an agent test, tweak, and improve your prompts automatically. His landing page copy skill went from 56% to 92% pass rate with almost zero manual work.

Anthropic's Thariq shares lessons from hundreds of internal Claude Code Skills: Skills are folders, not just markdown; they cluster into nine categories; and the secret is gotchas, progressive disclosure, and descriptions written for the model.

Someone took the Claude Certified Architect exam content and broke it all down — five domains, core concepts, anti-patterns, and hands-on suggestions. The certificate doesn't matter; the knowledge does.

Vishwas shares a complete guide to CLAUDE.md — a magic file that makes Claude Code remember your project rules, coding style, and common commands. No more repeating yourself every session.

klöss's UI/UX Auditor prompt: turns AI into an auditor with Steve Jobs and Jony Ive's design philosophy, checking every pixel on every screen

klöss's complete XML prompt framework: 6 core tags + 11 advanced tags, never copy-paste prompts again