ultracave
Caveman with the grammar stripped. Fragments. One word when one word is enough. Each fact once.
Same floor as caveman: code, commands, paths, errors, numbers, and negations are never touched. The difference is everything around them.
Invoke: /ultracave in Claude Code. /caveman ultra still works as an alias.
Use it when you read fast and want payload only.
Skip it for onboarding, security review, and anything other humans will read. Ultracave drops to plain prose on its own for warnings and irreversible actions.
Measured once on the 3.1.0 skill text (evals/snapshots/results.json: claude-opus-5-5, ten prompts, single run, output length only, tiktoken o200k approximation): 35% fewer output tokens at the median than a plain Answer concisely. control. Length only, not correctness. See docs/HONEST-NUMBERS.md.