Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/ayushcodes10/echo-memnpx agentmods add skills/ayushcodes10/echo-mem/skill-builderWrote 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.
[](https://agentmods.dev/skills/ayushcodes10/echo-mem/skill-builder)<a href="https://agentmods.dev/skills/ayushcodes10/echo-mem/skill-builder"><img src="https://agentmods.dev/badge/skills/ayushcodes10/echo-mem/skill-builder/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.
<a href="https://agentmods.dev/skills/ayushcodes10/echo-mem/skill-builder"><img src="https://agentmods.dev/badge/skills/ayushcodes10/echo-mem/skill-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00047 | $0.05287 |
| Opus 5.5 | $0.00019 | $0.02115 |
| Sonnet 5.5 | $0.00009 | $0.01057 |
| Haiku 4.5 | $0.00005 | $0.00529 |
Grade A, and why
Skill Builder 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.
This is a copy
100% identical to Skill Builder — 66 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.
How it starts
The opening of the file, as written. The whole thing — 911 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Builder
What This Skill Does
Creates production-ready Codex Skills with proper YAML frontmatter, progressive disclosure architecture, and complete file/folder structure. This skill guides you through building skills that Codex can autonomously discover and use across all surfaces (Codex.ai, Codex, SDK, API).
Prerequisites
- Codex 2.0+ or Codex.ai with Skills support
- Basic understanding of Markdown and YAML
- Text editor or IDE
Quick Start
Creating Your First Skill
# 1. Create skill directory (MUST be at top level, NOT in subdirectories!)
mkdir -p ~/.Codex/skills/my-first-skill
# 2. Create SKILL.md with proper format
cat > ~/.Codex/skills/my-first-skill/SKILL.md << 'EOF'
---
name: "My First Skill"
description: "Brief description of what this skill does and when Codex should use it. Maximum 1024 characters."
---
# My First Skill
## What This Skill Does
[Your instructions here]
## Quick Start
[Basic usage]
EOF
# 3. Verify skill is detected
# Restart Codex or refresh Codex.ai
Complete Specification
📋 YAML Frontmatter (REQUIRED)
Every SKILL.md must start with YAML frontmatter containing exactly two required fields:
---
name: "Skill Name" # REQUIRED: Max 64 chars
description: "What this skill does # REQUIRED: Max 1024 chars
and when Codex should use it." # Include BOTH what & when
---
Field Requirements
name (REQUIRED):
- Type: String
- Max Length: 64 characters
- Format: Human-friendly display name
- Usage: Shown in skill lists, UI, and loaded into Codex's system prompt
- Best Practice: Use Title Case, be concise and descriptive
- Examples:
- ✅ "API Documentation Generator"
- ✅ "React Component Builder"
- ✅ "Database Schema Designer"
- ❌ "skill-1" (not descriptive)
- ❌ "This is a very long skill name that exceeds sixty-four characters" (too long)
description (REQUIRED):
- Type: String
- Max Length: 1024 characters
- Format: Plain text or minimal markdown
- Content: MUST include:
- What the skill does (functionality)
- When Codex should invoke it (trigger conditions)
- Usage: Loaded into Codex's system prompt for autonomous matching
- Best Practice: Front-load key trigger words, be specific about use cases
- Examples:
- ✅ "Generate OpenAPI 3.0 documentation from Express.js routes. Use when creating API docs, documenting endpoints, or building API specifications."
- ✅ "Create React functional components with TypeScript, hooks, and tests. Use when scaffolding new components or converting class components."
- ❌ "A comprehensive guide to API documentation" (no "when" clause)
- ❌ "Documentation tool" (too vague)
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.
- 1mo ago Changed · +1 tokens per session f231b059f596
- 1mo ago First seen · 911 lines · 46 tokens per session scan A 3ebb2c70e4d8
Skill Builder is a skill published in the GitHub repository ayushcodes10/echo-mem (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 47 tokens to every session and 5,287 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to Skill Builder, differing in 66 lines, and is treated as a copy.
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