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 jaktestowac/awesome-copilot-for-testers --skill creating-custom-agentsgit clone --depth 1 https://github.com/jaktestowac/awesome-copilot-for-testersWrote 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/jaktestowac/awesome-copilot-for-testers/creating-custom-agents)<a href="https://agentmods.dev/skills/jaktestowac/awesome-copilot-for-testers/creating-custom-agents"><img src="https://agentmods.dev/badge/skills/jaktestowac/awesome-copilot-for-testers/creating-custom-agents/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/jaktestowac/awesome-copilot-for-testers/creating-custom-agents"><img src="https://agentmods.dev/badge/skills/jaktestowac/awesome-copilot-for-testers/creating-custom-agents.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00052 | $0.01039 |
| Opus 5.5 | $0.00021 | $0.00416 |
| Sonnet 5.5 | $0.00010 | $0.00208 |
| Haiku 4.5 | $0.00005 | $0.00104 |
Grade A, and why
creating-custom-agents 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 — 132 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Creating Custom Agents
Use this skill when a reusable role needs its own identity instead of hiding inside a prompt or a skill. It helps create custom agents that are focused, tool-aware, and easy to extend without scope creep.
When to Use
Use this skill when the user asks for things like:
- "create a custom agent for this workflow"
- "design an agent with limited tools"
- "turn this expert role into a
.agent.mdfile" - "define how an orchestrator should delegate to specialists"
- "fix an agent that is too broad or too verbose"
Typical scenarios:
- creating a new single-purpose agent
- building a specialist for a multi-agent workflow
- tightening an existing agent's scope and tool access
- preparing a reusable example agent for a shared repository
Outcome Standard
A strong custom agent contribution usually includes:
- a crisp role and mission
- a deliberate toolset rather than blanket access
- clear guidance on when the agent should be used
- boundaries that stop the agent from absorbing work better handled by prompts, skills, or instructions
- an install-ready
.agent.mdfile plus reference material
Agent Design Rules
- Role first - define who the agent is and what it owns before writing any workflow guidance.
- Minimal tools - only grant the tools the role genuinely needs.
- Skills for procedure - reference skills for reusable workflows instead of stuffing the entire playbook into the agent.
- Prompts for entrypoints - if users need a guided starting command, create a prompt file in addition to the agent.
- Boundaries matter - explain what the agent should not do, especially when nearby agents overlap.
Workflow
Phase 0: Decide whether an agent is the right primitive
Choose an agent only when the work needs a persistent role, a specific tool profile, or a distinct collaboration pattern. If the need is only a reusable task starter, prefer a prompt. If the need is procedural knowledge, prefer a skill.
Phase 1: Study adjacent artifacts
What ships with it
3 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.
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 · 132 lines · 52 tokens per session scan A 30abb7d3265c
creating-custom-agents is a skill published in the GitHub repository jaktestowac/awesome-copilot-for-testers (118 stars, last pushed 2mo ago), licensed MIT. It adds 52 tokens to every session and 1,039 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 2026-08-30.
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