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 skills/saski/arnesto/create-subagentnpx skills add saski/arnesto --skill create-subagentgit clone --depth 1 https://github.com/saski/arnestoWrote 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/saski/arnesto/create-subagent)<a href="https://agentmods.dev/skills/saski/arnesto/create-subagent"><img src="https://agentmods.dev/badge/skills/saski/arnesto/create-subagent.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 | $0.00048 | $0.01385 |
| Opus 5 | $0.00024 | $0.00692 |
| Sonnet 5 | $0.00010 | $0.00277 |
| Haiku 4.5 | $0.00005 | $0.00138 |
Grade A, and why
create-subagent 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 yesterday.
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 create-subagent — 0 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 — 226 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Creating Custom Subagents
This skill guides you through creating custom subagents for Cursor. Subagents are specialized AI assistants that run in isolated contexts with custom system prompts.
When to Use Subagents
Subagents help you:
- Preserve context by isolating exploration from your main conversation
- Specialize behavior with focused system prompts for specific domains
- Reuse configurations across projects with user-level subagents
Inferring from Context
If you have previous conversation context, infer the subagent's purpose and behavior from what was discussed. Create the subagent based on specialized tasks or workflows that emerged in the conversation.
Subagent Locations
| Location | Scope | Priority |
|---|---|---|
.cursor/agents/ |
Current project | Higher |
~/.cursor/agents/ |
All your projects | Lower |
When multiple subagents share the same name, the higher-priority location wins.
Project subagents (.cursor/agents/): Ideal for codebase-specific agents. Check into version control to share with your team.
User subagents (~/.cursor/agents/): Personal agents available across all your projects.
Subagent File Format
Create a .md file with YAML frontmatter and a markdown body (the system prompt):
---
name: code-reviewer
description: Reviews code for quality and best practices
---
You are a code reviewer. When invoked, analyze the code and provide
specific, actionable feedback on quality, security, and best practices.
Required Fields
| Field | Description |
|---|---|
name |
Unique identifier (lowercase letters and hyphens only) |
description |
When to delegate to this subagent (be specific!) |
Writing Effective Descriptions
The description is critical - the AI uses it to decide when to delegate.
# ❌ Too vague
description: Helps with code
# ✅ Specific and actionable
description: Expert code review specialist. Proactively reviews code for quality, security, and maintainability. Use immediately after writing or modifying code.
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.
- yesterday First seen · 226 lines · 48 tokens per session scan A ab46a80f90cb
create-subagent is a skill published in the GitHub repository saski/arnesto (5 stars, last pushed 9d ago), licensed Unlicense. It adds 48 tokens to every session and 1,385 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to create-subagent, differing in 0 lines, and is treated as a copy.
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