caveman is a skill and proxy for coding agents that shortens unnecessary explanatory prose so agents use fewer tokens while leaving code, commands, paths, and error messages unchanged. It is for people using coding agents who want terse responses and lower token use, including with Claude-based workflows. The catalogue entries contain its skills, commands, agents, instructions, and plugins.
Borrowing it
Nothing to install: this file belongs to JuliusBrussee/caveman. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/JuliusBrussee/caveman/main/CLAUDE.mdgit clone --depth 1 https://github.com/JuliusBrussee/cavemanWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/juliusbrussee/caveman/claude-md)<a href="https://agentmods.dev/instructions/juliusbrussee/caveman/claude-md"><img src="https://agentmods.dev/badge/instructions/juliusbrussee/caveman/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/juliusbrussee/caveman/claude-md"><img src="https://agentmods.dev/badge/instructions/juliusbrussee/caveman/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.11984 | $0.11984 |
| Opus 5.5 | $0.04794 | $0.04794 |
| Sonnet 5.5 | $0.02397 | $0.02397 |
| Haiku 4.5 | $0.01198 | $0.01198 |
Grade B, and why
caveman CLAUDE.md scanned grade B with 3 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Reads agent configuration directoriesmediumAgent snooping
.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.
| Antigravity CLI (`agy`) | `--only antigravity-cli` stages a temp plugin (`plugin.json`, the nine skills, `rules/AGENTS.md` = `src/rules/caveman-activate.md`) and runs `agy plugin install <dir>`; agy copies it to `~/.ge Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
The `install.sh` / `install.ps1` shims at the repo root delegate to `installer/install.js` via `node` (local clone) or `npx -y github:JuliusBrussee/caveman` (curl|bash). No legacy fallback path remains — earlier `install Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
**The stdin contour is load-bearing.** Activation runs on the first COMPLETE JSON object, not at EOF, with a 2000ms `PAYLOAD_WATCHDOG_MS` backstop and `process.stdin.unref()` in `finish()`. `pause()` alone is not enough How it starts
The opening of the file, as written. The whole thing — 436 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md — caveman
README is a product artifact
README = product front door. Non-technical people read it to decide if caveman worth install. Treat like UI copy.
Rules for any README change:
- Readable by non-AI-agent users. If you write "SessionStart hook injects system context," invisible to most — translate it.
- Keep Before/After examples first. That the pitch.
- Install table always complete + accurate. One broken install command costs real user.
- What You Get table must sync with actual code. Feature ships or removed → update table.
- Preserve voice. Caveman speak in README on purpose. "Brain still big." "Cost go down forever." "One rock. That it." — intentional brand. Don't normalize.
- Benchmark numbers from real runs in
benchmarks/andevals/. Never invent or round. Re-run if doubt. - Adding new agent to install table → add detail block in
<details>section below. - Readability check before any README commit: would non-programmer understand + install within 60 seconds?
Project overview
Caveman makes AI coding agents respond in compressed caveman-style prose while preserving technical substance, code, commands, and exact errors. Publish no reduction or quality-equivalence percentage without a committed reviewed benchmark. Ships as Claude Code plugin, Codex plugin, Gemini CLI extension, and agent rule files for Cursor, Windsurf, Cline, Copilot, and other profiles via npx skills.
Repository routing
This repo is source of truth for Caveman skills, Engine, and MV3 directive
extension. Agent SDK + initializer work belongs in
/Users/julb/Desktop/GitHub/caveman-agent-sdk
(JuliusBrussee/agent-sdk). Proprietary Pebble runtime, policy, sessions, TUI,
distribution, and conformance work belongs in
/Users/julb/Desktop/GitHub/caveman-coding-agent
(intended JuliusBrussee/caveman-coding-agent). Browse driver/MCP/benchmark/plugin work
belongs in /Users/julb/Desktop/GitHub/caveman-browse
(JuliusBrussee/caveman-browse). The matching browse/ directory here is a
consumer copy (it still builds the caveman-browse release binary); edit only
for pinned integration, migration/removal, or an explicitly requested
cross-repo sync.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago Changed · +101 tokens per session a90879c1c898
- 7d ago Changed · +17 lines · +1,783 tokens per session scan A → B f1fe7a7d329d
- 13d ago Changed · +1 lines · +559 tokens per session c686864b036c
- 15d ago Changed · -3 lines · -58 tokens per session 0eb4deb4cd86
- 1mo ago Changed · +1 lines · +59 tokens per session b9791981d963
- 1mo ago Changed · +1 lines · +195 tokens per session 819a9263ba75
- 1mo ago Changed · +3 lines · +54 tokens per session 1f3e63d63f97
- 1mo ago First seen · 416 lines · 9,291 tokens per session scan A ce0a6ca0e980
caveman CLAUDE.md is an instructions file published in the GitHub repository JuliusBrussee/caveman (112,527 stars, last pushed yesterday), licensed Apache-2.0. It adds 11,984 tokens to every session, about $0.0479 per session on Opus 5.5. A static security scan graded it B with 3 findings (reads agent configuration directories, makes network calls, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other instructions, from other repositories
vscode buildNext.instructions.md
Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).