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.
npx skills add trsdn/github-copilot-agent --skill copilot-skill-buildergit clone --depth 1 https://github.com/trsdn/github-copilot-agentWrote 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-agent/copilot-skill-builder)<a href="https://agentmods.dev/skills/trsdn/github-copilot-agent/copilot-skill-builder"><img src="https://agentmods.dev/badge/skills/trsdn/github-copilot-agent/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-agent/copilot-skill-builder"><img src="https://agentmods.dev/badge/skills/trsdn/github-copilot-agent/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 | $0.00058 | $0.01418 |
| Opus 5.5 | $0.00023 | $0.00567 |
| Sonnet 5.5 | $0.00012 | $0.00284 |
| Haiku 4.5 | $0.00006 | $0.00142 |
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 — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Builder
This skill helps you create, organize, and maintain Agent Skills for GitHub Copilot and compatible AI agents.
What are Agent Skills?
Agent Skills are folders containing a SKILL.md file plus optional scripts, examples, and resources. They teach specialized capabilities and workflows to AI agents. Skills are:
- Portable: Work across VS Code, Copilot CLI, and Copilot coding agent
- Composable: Multiple skills can work together
- Efficient: Loaded on-demand based on relevance to the current task
- Open standard: Based on agentskills.io
Skill locations
| Type | Location | Use case |
|---|---|---|
| Project skills | .github/skills/<skill-name>/ |
Shared with the repository |
| Personal skills | ~/.copilot/skills/<skill-name>/ |
Private to your machine |
SKILL.md file format
Every skill requires a SKILL.md file with YAML frontmatter:
---
name: skill-name
description: Description of what the skill does and when to use it (max 1024 chars)
---
# Skill Instructions
Detailed instructions, guidelines, and examples...
Frontmatter fields
| Field | Required | Description |
|---|---|---|
name |
Yes | Unique identifier. Lowercase, hyphens for spaces, max 64 chars. Must match parent directory name |
description |
Yes | What the skill does and when to use it. Be specific to help Copilot decide when to load. Max 1024 chars |
argument-hint |
No | Hint text shown in chat input when invoked as a slash command |
user-invocable |
No | Controls / slash command visibility (default: true). Set to false for background skills |
disable-model-invocation |
No | Controls auto-loading by Copilot (default: false). Set to true for manual-only skills |
license |
No | License name or reference to a bundled license file (from agentskills.io spec) |
compatibility |
No | Environment requirements — intended product, system packages, network access. Max 500 chars |
metadata |
No | Arbitrary key-value mapping for additional metadata (e.g., author, version) |
allowed-tools |
No | Space-delimited list of pre-approved tools the skill may use (experimental) |
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 · 165 lines · 58 tokens per session scan A 470918c3b114
copilot-skill-builder is a skill published in the GitHub repository trsdn/github-copilot-agent (3 stars, last pushed 1mo ago), licensed MIT. It adds 58 tokens to every session and 1,418 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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