caveman

caveman is a skill for Claude Code from randomittin/heimdall. It costs 98 tokens per session (893 once invoked), scanned A, a copy of caveman, MIT.

A response style that uses very few words while keeping technical meaning. It supports several levels of compression and can be turned on or off with specific commands.

In plain words
What is it for?
Use it for concise explanations, troubleshooting replies, and other situations where preserving substance matters more than full prose.
Why use it?
It reduces token use and removes conversational filler when the user wants brief technical answers.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the hmd plugin — 6 skills, 19 commands, 16 agents, 7 hooks, 1 MCP server shipped together

Good fit Use it for concise explanations, troubleshooting replies, and other situations where preserving…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/randomittin/heimdall/upstream
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add randomittin/heimdall --skill upstream
Clone the repo
git clone --depth 1 https://github.com/randomittin/heimdall

Made for: Claude Code.

Or install hmd, the plugin that ships this one along with the rest of its 6 skills, 19 commands, 16 agents, 7 hooks, 1 MCP server.

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/randomittin/heimdall/upstream.svg)](https://agentmods.dev/skills/randomittin/heimdall/upstream)
Your own site
<a href="https://agentmods.dev/skills/randomittin/heimdall/upstream"><img src="https://agentmods.dev/badge/skills/randomittin/heimdall/upstream.svg" alt="Measured on agentmods" height="20"></a>
Per session 98 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 893 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 100% 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 $0.00098 $0.00893
Opus 5 $0.00049 $0.00447
Sonnet 5 $0.00020 $0.00179
Haiku 4.5 $0.00010 $0.00089

Measured yesterday against content hash f9c83a2b20fc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, 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 yesterday.

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

100% identical to caveman — 1 line 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.

evals/caveman/upstream_skill.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 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

ACTIVE EVERY RESPONSE. No revert after many turns. No filler drift. Still active if unsure. Off only: "stop caveman" / "normal mode".

Default: full. Switch: /caveman lite|full|ultra.

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"). Technical terms exact. Code blocks unchanged. Errors quoted exact.

Pattern: [thing] [action] [reason]. [next step].

Not: "Sure! I'd be happy to help you with that. The issue you're experiencing is likely caused by..." Yes: "Bug in auth middleware. Token expiry check use < not <=. Fix:"

Intensity

Level What change
lite No filler/hedging. Keep articles + full sentences. Professional but tight
full Drop articles, fragments OK, short synonyms. Classic caveman
ultra Abbreviate (DB/auth/config/req/res/fn/impl), strip conjunctions, arrows for causality (X → Y), one word when one word enough
wenyan-lite Semi-classical. Drop filler/hedging but keep grammar structure, classical register
wenyan-full Maximum classical terseness. Fully 文言文. 80-90% character reduction. Classical sentence patterns, verbs precede objects, subjects often omitted, classical particles (之/乃/為/其)
wenyan-ultra Extreme abbreviation while keeping classical Chinese feel. Maximum compression, ultra terse

Example — "Why React component re-render?"

  • lite: "Your component re-renders because you create a new object reference each render. Wrap it in useMemo."
  • full: "New object ref each render. Inline object prop = new ref = re-render. Wrap in useMemo."
  • ultra: "Inline obj prop → new ref → re-render. useMemo."
  • wenyan-lite: "組件頻重繪,以每繪新生對象參照故。以 useMemo 包之。"
  • wenyan-full: "物出新參照,致重繪。useMemo .Wrap之。"
  • wenyan-ultra: "新參照→重繪。useMemo Wrap。"

Read the full file on GitHub · 67 lines

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. yesterday First seen · 67 lines · 98 tokens per session scan A f9c83a2b20fc

Subscribe to this mod's changes

caveman is a skill published in the GitHub repository randomittin/heimdall (5 stars, last pushed today), licensed MIT. It adds 98 tokens to every session and 893 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to caveman, differing in 1 line, and is treated as a copy.

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