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 agentmods add instructions/thesethrose/copilot-skills/fastifygit clone --depth 1 https://github.com/TheSethRose/Copilot-SkillsWrote 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/instructions/thesethrose/copilot-skills/fastify)<a href="https://agentmods.dev/instructions/thesethrose/copilot-skills/fastify"><img src="https://agentmods.dev/badge/instructions/thesethrose/copilot-skills/fastify.svg" alt="Measured on agentmods" 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 | $0.00286 | $0.00286 |
| Opus 5 | $0.00143 | $0.00143 |
| Sonnet 5 | $0.00057 | $0.00057 |
| Haiku 4.5 | $0.00029 | $0.00029 |
Grade A, and why
Copilot-Skills fastify.instructions.md 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 4d 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.
What it actually says
Fastify Instructions
Auto-loaded when: Working with files matching: **/*.js, **/*.ts, **/fastify*
Default Behaviors
When working with fastify:
- Follow Official Patterns: Use patterns from official fastify documentation
- Code Quality: Follow fastify best practices and conventions
- Error Handling: Implement robust error handling appropriate for fastify
- Documentation: Include inline comments for complex fastify usage
Common Workflows
Setup & Installation
Check references/getting_started.md for:
- Installation steps
- Configuration options
- Initial setup
Development
- Reference official documentation patterns
- Use type-safe code when applicable
- Follow fastify naming conventions
- Test thoroughly
Debugging
Common issues and solutions documented in references/ files.
Quality Guidelines
- ✅ Use official fastify APIs and patterns
- ✅ Follow community best practices
- ✅ Write maintainable, readable code
- ✅ Include error handling
- ⚠️ Avoid deprecated features
- ⚠️ Don't bypass fastify safety features
Resources
- Skill prompt:
.github/prompts/fastify.skill.prompt.md - References:
.github/copilot-skills/backend/fastify/references/ - Official docs: https://fastify.dev/docs/latest/
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.
- 4d ago First seen · 48 lines · 286 tokens per session scan A 054391bb9a23
Copilot-Skills fastify.instructions.md is an instructions file published in the GitHub repository TheSethRose/Copilot-Skills (3 stars, last pushed 8mo ago), licensed MIT. It adds 286 tokens to every session, about $0.0014 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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