ultrapex

ultrapex is a skill for Claude Code from coroboros/agent-skills. It costs 57 tokens per session (1,869 once invoked), scanned A, original, MIT.

An implementation workflow for completing a coding task from scoping through verification, with extra checks by independent subagents when needed.

In plain words
What is it for?
It helps implement, build, add, fix, or refactor software and verify the result with checks suited to the task’s risk and complexity.
Why use it?
It helps catch unsupported claims, defects, and untested changes before the work is considered complete.

Skill for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: mentions subagents.

Part of the workflow-skills plugin — 4 skills shipped together

Good fit It helps implement, build, add, fix, or refactor software and verify the result with checks suited to the task’s risk and complexity.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/coroboros/agent-skills/ultrapex
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 coroboros/agent-skills --skill ultrapex
Clone the repo
git clone --depth 1 https://github.com/coroboros/agent-skills

Made for: Claude Code.

Or install workflow-skills, the plugin that ships this one along with the rest of its 4 skills.

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 ultrapex

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/coroboros/agent-skills/ultrapex"><img src="https://agentmods.dev/badge/skills/coroboros/agent-skills/ultrapex.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,869 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 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 5.1 $0.00057 $0.01869
Opus 5 $0.00028 $0.00934
Sonnet 5 $0.00011 $0.00374
Haiku 4.5 $0.00006 $0.00187

Measured today against content hash 4bc3d1a39cc1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

ultrapex 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 today.

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/ultrapex/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ultrapex

Critical — Adversarial verification

Verify consequential findings and decisions before acting on them.

  • Seek counterexamples and independent evidence for load-bearing or contested claims. Use fresh reviewers when available and useful; label sequential self-review as less independent.
  • Resolve material findings by correction, evidence-backed refutation, or an explicit remaining risk. Never silently drop them.
  • Evidence decides, not reviewer counts or confidence alone. One reproducible defect can invalidate a conclusion.
  • Scale verification to the stakes. Keep settled facts settled and reversible, low-impact checks light.

Important — Engineering discipline

Apply these rules when writing, editing, or proposing code.

  • Solve the accepted problem with the smallest complete change. Reuse existing mechanisms; preserve unrelated work. Validate external inputs and real failure states.
  • Read the affected implementation, callers, and shared utilities before editing. Ground code claims in inspected evidence.
  • Implement the general behavior. Tests must distinguish correct behavior from the defect; never hard-code to fixtures or preserve a demonstrably wrong test.
  • Carry scope, corrections, and existing authorization through handoffs. Run applicable required checks; repeat them only for changed behavior or unresolved failures.

Critical — Label hygiene

Remove private planning labels and process narration from shipped code and prose. State the domain behavior directly.

  • Planning labels — replace WS-N, Phase-A, Step-3, and private plan names with domain terms.
  • Process narration — remove authoring history and references that require private planning context. Explain the resulting behavior or constraint.

Read the full file on GitHub · 117 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. today Changed · -55 tokens per session 4bc3d1a39cc1
  2. 8d ago First seen · 117 lines · 112 tokens per session scan A 74c330606bbf

Subscribe to this mod's changes

ultrapex is a skill published in the GitHub repository coroboros/agent-skills (4 stars, last pushed 2d ago), licensed MIT. It adds 57 tokens to every session and 1,869 once invoked, about $0.0003 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 2026-08-31.

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