create-subagent

A guide for creating custom subagents: separate AI helpers with their own instructions for a specific kind of work.

In plain words
What is it for?
It is for setting up code reviewers, debuggers, research helpers, or other task-focused assistants in Cursor.
Why use it?
It helps keep specialized tasks separate from the main conversation and lets you reuse the same helper across projects.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/xyruscode/ai-sync/create-subagent
Any agent
npx skills add XyrusCode/ai-sync --skill create-subagent
Clone the repo
git clone --depth 1 https://github.com/XyrusCode/ai-sync

Made for: Claude Code, Codex.

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,385 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

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.

ModelPer sessionOnce 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

Measured yesterday against content hash ab46a80f90cb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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.

Origin

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.

skills/create-subagent/SKILL.md · 226 lines

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.

Read the full file on GitHub · 226 lines

Changes

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.

  1. yesterday First seen · 226 lines · 48 tokens per session scan A ab46a80f90cb

Subscribe to this mod's changes

create-subagent is a skill published in the GitHub repository XyrusCode/ai-sync (2 stars, last pushed 2d ago), licensed MIT. 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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