builtin-agent-skill

builtin-agent-skill is a skill for Claude Code, Codex from samugit83/redamon. It costs 150 tokens per session (1,276 once invoked), scanned A, original, MIT.

A workflow for adding a built-in security attack technique to an AI agent, including its classification, instructions, project setting, and chat interface entry.

In plain words
What is it for?
It is for adding attack workflows such as SSRF, XXE, or RCE to the agent, with routing keywords, toggles, badges, tooltips, and example prompts.
Why use it?
It helps every part of the product recognize and expose the new technique, avoiding silent omissions that make it partly work.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/samugit83/redamon/builtin-agent-skill
Any agent
npx skills add samugit83/redamon --skill builtin-agent-skill
Clone the repo
git clone --depth 1 https://github.com/samugit83/redamon

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 builtin-agent-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/samugit83/redamon/builtin-agent-skill.svg)](https://agentmods.dev/skills/samugit83/redamon/builtin-agent-skill)
Your own site
<a href="https://agentmods.dev/skills/samugit83/redamon/builtin-agent-skill"><img src="https://agentmods.dev/badge/skills/samugit83/redamon/builtin-agent-skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 150 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,276 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00150 $0.01276
Opus 5 $0.00075 $0.00638
Sonnet 5 $0.00030 $0.00255
Haiku 4.5 $0.00015 $0.00128

Measured 4d ago against content hash 5ff098f3da93, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

builtin-agent-skill 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 4d 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.

skills/builtin-agent-skill/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

When to Use

  • Adding a first-class attack technique the agent classifies and follows a workflow for.

For a user-uploadable workflow, use add-community-skill instead. For a tool the agent calls, use agentic-tool-integration. For per-skill tunable defaults, use project-settings-cascade.


Critical Rules

  • ALWAYS add the skill id to KNOWN_ATTACK_PATHS in agentic/state.py. It is the Pydantic validator's allowlist; miss it and the classifier's output is rejected at runtime even though every other layer is wired.
  • NEVER skip layers 8 and 9 (the chat-drawer layers). They live in webapp and produce no error when forgotten: the skill classifies and badges, but the drawer tooltip and one-click example prompts are silently missing. Layer 8 = BUILT_IN_SKILLS in attack-skills/available/route.ts; Layer 9 = a SESubGroup in suggestionData.ts.
  • NEVER let classification keywords overlap an existing skill. Every enabled built-in competes for the same user message; overlapping keywords (e.g. saying "SQL" in an SSRF section) make both skills mis-route. Disambiguate in the "Key distinction" line of the section in classification.py.
  • ALWAYS gate the workflow on the required tool inside _inject_builtin_skill_workflow() (agentic/prompts/init.py:509): and "<tool>" in allowed_tools. Without the guard the agent gets instructions for a tool TOOL_PHASE_MAP blocks in that phase.
  • NEVER assume existing projects inherit the new skill. builtIn is a strict has-key check; existing projects need a jsonb update to attackSkillConfig.
  • Pick the snake_case id once and use that exact literal in all 9 layers. grep -rn "<skill_id>" webapp/src agentic must show it everywhere before you rebuild (an existing id like cve_exploit spans ~38 files).

Read the full file on GitHub · 86 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. 4d ago First seen · 86 lines · 150 tokens per session scan A 5ff098f3da93

Subscribe to this mod's changes

builtin-agent-skill is a skill published in the GitHub repository samugit83/redamon (2,380 stars, last pushed yesterday), licensed MIT. It adds 150 tokens to every session and 1,276 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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