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/trsdn/github-copilot-clinpx agentmods add skills/trsdn/github-copilot-cli/copilot-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/trsdn/github-copilot-cli/copilot-skill-builder)<a href="https://agentmods.dev/skills/trsdn/github-copilot-cli/copilot-skill-builder"><img src="https://agentmods.dev/badge/skills/trsdn/github-copilot-cli/copilot-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/trsdn/github-copilot-cli/copilot-skill-builder"><img src="https://agentmods.dev/badge/skills/trsdn/github-copilot-cli/copilot-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 | $0.00061 | $0.01175 |
| Opus 5.5 | $0.00024 | $0.00470 |
| Sonnet 5.5 | $0.00012 | $0.00235 |
| Haiku 4.5 | $0.00006 | $0.00118 |
Grade A, and why
copilot-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.
How it starts
The opening of the file, as written. The whole thing — 151 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Builder
This skill helps you create well-structured Agent Skills for GitHub Copilot CLI.
When to use this skill
- User wants to create a new Agent Skill
- User asks about the SKILL.md format or best practices
- User wants to understand how skills work in Copilot CLI
- User needs to debug or improve an existing skill
SKILL.md Format
Every skill lives in its own directory and must contain a SKILL.md file:
.github/skills/<skill-name>/
├── SKILL.md # Required: skill instructions
├── scripts/ # Optional: helper scripts
├── examples/ # Optional: example files
└── templates/ # Optional: template files
SKILL.md Structure
---
name: skill-name
description: What the skill does and when Copilot should use it. Be specific to help Copilot decide when to load this skill.
license: MIT
allowed-tools: read, grep
user-invocable: true
disable-model-invocation: false
---
# Skill Title
Overview of what this skill accomplishes.
## When to use this skill
- Specific trigger 1
- Specific trigger 2
## Step-by-step procedure
1. First step
2. Second step
## Examples
### Example 1: Description
...
## References
- [Link to relevant docs](https://...)
Frontmatter Fields
| Field | Required | Description |
|---|---|---|
name |
✅ Yes | Unique identifier, lowercase with hyphens, max 64 chars |
description |
✅ Yes | What it does and when to use it, max 1024 chars |
license |
❌ No | License information for the skill |
allowed-tools |
❌ No | Comma-separated string or YAML array of tools to allow when active |
user-invocable |
❌ No | Whether users can invoke the skill with /skill-name; defaults to true |
disable-model-invocation |
❌ No | Prevents automatic model invocation; defaults to false |
Skill Locations
| Type | Location | Scope |
|---|---|---|
| Project skills | .github/skills/<name>/SKILL.md |
Current repository |
| Project skills | .agents/skills/<name>/SKILL.md |
Current repository, cross-agent standard |
| Project skills | .claude/skills/<name>/SKILL.md |
Current repository, Claude-compatible |
| Personal skills | ~/.copilot/skills/<name>/SKILL.md |
All your projects |
| Personal skills | ~/.agents/skills/<name>/SKILL.md |
Shared across agent tools |
| Custom locations | COPILOT_SKILLS_DIRS |
Additional comma-separated directories |
| Plugin skills | <plugin>/skills/<name>/SKILL.md |
Installed plugin scope |
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.
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 First seen · 151 lines · 61 tokens per session scan A cc22e6c20f75
copilot-skill-builder is a skill published in the GitHub repository trsdn/github-copilot-cli (1 stars, last pushed 3mo ago), licensed MIT. It adds 61 tokens to every session and 1,175 once invoked, about $0.0002 per session on Opus 5.5. 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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