APEX: Skill for Claude Code

.agents/skills/apex-tier3/SKILL.md

apex-tier3 is a skill for Claude Code from OthmanAdi/APEX. It costs 75 tokens per session (889 once invoked), scanned A, original, MIT.

An interactive pair-programming mode for difficult software work. The agent proposes actions and explains its reasoning, while the developer confirms, changes, or rejects each step.

In plain words
What is it for?
Designing system architecture, investigating serious production bugs, exploring unfamiliar problems, and learning through the implementation process.
Why use it?
It keeps important decisions visible and reviewable when the problem is unclear or mistakes would be costly.

Skill for Claude Code

Written for Claude Code: ${CLAUDE_SKILL_DIR} variable. Also seen: installed under .agents/ (shared by several agents); mentions AGENTS.md.

This is OthmanAdi/APEX's own configuration. It tells Claude Code how to work on APEX 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 APEX configures →

Reuse

Borrowing it

Nothing to install: this file belongs to OthmanAdi/APEX. 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/OthmanAdi/APEX/main/.agents/skills/apex-tier3/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/OthmanAdi/APEX

Made for: Claude Code.

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 apex-tier3

README.md
[![agentmods](https://agentmods.dev/badge/skills/othmanadi/apex/apex-tier3.svg)](https://agentmods.dev/skills/othmanadi/apex/apex-tier3)
Your own site
<a href="https://agentmods.dev/skills/othmanadi/apex/apex-tier3"><img src="https://agentmods.dev/badge/skills/othmanadi/apex/apex-tier3.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 889 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 $0.00075 $0.00889
Opus 5 $0.00037 $0.00445
Sonnet 5 $0.00015 $0.00178
Haiku 4.5 $0.00007 $0.00089

Measured 8d ago against content hash dbe97f78324a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

apex-tier3 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 8d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/validate.ps1, scripts/validate.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

.agents/skills/apex-tier3/SKILL.md · 110 lines

How it starts

The opening of the file, as written. The whole thing — 110 lines — stays where its author put it; the contents beside it link to each section on GitHub.

APEX Tier 3 — Pair Mode

Work side-by-side with the human in real-time. Every significant decision is discussed. The agent proposes, the human approves or redirects.

When to Use

Use Tier 3 when:

  • Designing new architecture from scratch
  • Debugging a critical production issue
  • The problem space is ambiguous or exploratory
  • The human wants to learn from the process
  • Stakes are high and mistakes are expensive

Interaction Protocol

The Propose-Confirm Loop

Every action follows this pattern:

  1. Agent proposes — "I think we should do X because Y. Here's what that looks like..."
  2. Human confirms, modifies, or rejects — "Yes" / "Do X but change Z" / "No, try A instead"
  3. Agent executes — Implements the confirmed approach
  4. Agent reports — "Done. Here's what changed. Ready for next step."

Rules of Engagement

  • Never write more than 50 lines without checking in
  • Always explain WHY before proposing WHAT
  • Show alternatives when there's a genuine trade-off: "Option A gives us X but costs Y. Option B gives us Z but costs W."
  • Admit uncertainty — "I'm not confident about this approach because..." is always better than guessing
  • No yes-man behavior — If the human's suggestion has a flaw, say so respectfully with evidence

Workflow

Opening

Start by understanding the problem space:

Before we start, I need to understand:
1. What are we trying to achieve?
2. What constraints exist (time, tech, compatibility)?
3. What have you already tried or considered?
4. What does success look like?

During the Session

Maintain a running decision log:

## Decision Log

| # | Decision | Rationale | Alternatives Considered |
|---|----------|-----------|------------------------|
| 1 | Use Prisma over Drizzle | Team familiarity | Drizzle (faster), raw SQL (flexible) |
| 2 | REST over GraphQL | Simpler for this scope | GraphQL (flexible queries) |

After every significant block of work, run validation:

Read the full file on GitHub · 110 lines

Files

What ships with it

2 files 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. 8d ago First seen · 110 lines · 75 tokens per session scan A dbe97f78324a

Subscribe to this mod's changes

apex-tier3 is a skill published in the GitHub repository OthmanAdi/APEX (2 stars, last pushed 5mo ago), licensed MIT. It adds 75 tokens to every session and 889 once invoked, about $0.0004 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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