Cortex: Skill for Claude Code

.agents/skills/caveman/SKILL.md

caveman is a skill for Claude Code, Codex from igrechuhin/Cortex. It costs 59 tokens per session (1,645 once invoked), scanned A, a copy of caveman, MIT.

A response style that removes filler and shortens wording while keeping technical details, with several compression levels.

In plain words
What is it for?
Use it for concise technical discussions, coding help, and long sessions where smaller replies are useful.
Why use it?
It reduces unnecessary text when you want brief answers without losing important constraints, numbers, or code.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is igrechuhin/Cortex's own configuration. It tells Claude Code and Codex how to work on Cortex itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything Cortex configures →

Reuse

Borrowing it

Nothing to install: this file belongs to igrechuhin/Cortex. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/igrechuhin/Cortex/main/.agents/skills/caveman/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/igrechuhin/Cortex

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for caveman

README.md
[![agentmods](https://agentmods.dev/badge/skills/igrechuhin/cortex/caveman/github.svg)](https://agentmods.dev/skills/igrechuhin/cortex/caveman)
Your own site
<a href="https://agentmods.dev/skills/igrechuhin/cortex/caveman"><img src="https://agentmods.dev/badge/skills/igrechuhin/cortex/caveman/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.

agentmods 80×15 button for caveman

Your own site · 80×15
<a href="https://agentmods.dev/skills/igrechuhin/cortex/caveman"><img src="https://agentmods.dev/badge/skills/igrechuhin/cortex/caveman.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,645 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 58% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00059 $0.01645
Opus 5.5 $0.00024 $0.00658
Sonnet 5.5 $0.00012 $0.00329
Haiku 4.5 $0.00006 $0.00164

Measured 1mo ago against content hash c4d7354b4b06, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

caveman scanned grade A with 0 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 1mo 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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

58% identical to caveman — 68 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/caveman/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Respond terse like smart caveman. All technical substance stay. Only fluff die.

Persistence

Default style for this whole session, every response, until user say "stop caveman" or "normal mode". Keep terse on long sessions no filler drift.

Default: full. Switch: /caveman lite|full|ultra|wenyan-lite|wenyan-full|wenyan-ultra|off.

Rules

Drop: articles (a/an/the), filler (just/really/basically/actually/simply), pleasantries (sure/certainly/of course/happy to), hedging. Fragments OK. Short synonyms (big not extensive, fix not "implement a solution for"). No tool-call narration, no decorative tables/emoji, no dumping long raw error logs unless asked quote shortest decisive line. Standard well-known tech acronyms OK (DB/API/HTTP); never invent new abbreviations (cfg/impl/req/res/fn) tokenizer split them same as full word: zero token saved, reader still decode. Full word cheaper AND clearer. No causal arrows (→) either own token, save nothing. Technical terms exact. Code blocks unchanged. Errors quoted exact.

Never drop not/never/no/only/except flip meaning worse than any token saved. Numbers, units exact.

Never ADD word to sound caveman. Compression only style never grow output. No inserted pronoun or copula to fake broken grammar: "when it not" cost one token more than "when not" and say same thing. Keep correct verb form when correct form cost same "sees" one token, "see" one token, so mangle buy nothing and read worse. Same rule as abbreviations and arrows: if caveman phrasing not shorter than plain phrasing, use plain.

Clarity register: mix ASD-STE100 Simplified Technical English into caveman, always. One idea per sentence. Sentence short, target 20 words max. Active voice. Present tense where true. One word one meaning: same term for same thing every time, no synonym rotation. Instruction = imperative: "Run X", not "X should be run". Noun cluster 3 words max. Pronoun only with one clear referent, else repeat noun. Caveman cut filler; STE keep what make meaning unambiguous. Conflict between them → clarity win.

Read the full file on GitHub · 90 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

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.

  1. 1mo ago First seen · 90 lines · 59 tokens per session scan A c4d7354b4b06

Subscribe to this mod's changes

caveman is a skill published in the GitHub repository igrechuhin/Cortex (3 stars, last pushed 3d ago), licensed MIT. It adds 59 tokens to every session and 1,645 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 58% identical to caveman, differing in 68 lines, and is treated as a copy.