agent-customization

agent-customization is a skill for Claude Code, Codex from majiayu000/claude-skill-registry. It costs 92 tokens per session (824 once invoked), scanned A, original, MIT.

Guidance for creating and troubleshooting VS Code agent customization files, such as workspace instructions, prompts, custom agents, and skills. These files change how coding agents behave in a project.

In plain words
What is it for?
Use it to save coding preferences, configure file-matching rules, define custom agents and prompts, or diagnose ignored agent configuration.
Why use it?
It helps you choose the right customization type and find why instructions or skills are not being applied.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents; mentions AGENTS.md.

Good fit Use it to save coding preferences, configure file-matching rules, define custom agents and prompts, or diagnose ignored agent configuration.

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Install with agentmods
npx agentmods add skills/majiayu000/claude-skill-registry/agent-customization
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.

Any agent
npx skills add majiayu000/claude-skill-registry --skill agent-customization
Clone the repo
git clone --depth 1 https://github.com/majiayu000/claude-skill-registry

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for agent-customization

README.md
[![agentmods](https://agentmods.dev/badge/skills/majiayu000/claude-skill-registry/agent-customization/github.svg)](https://agentmods.dev/skills/majiayu000/claude-skill-registry/agent-customization)
Your own site
<a href="https://agentmods.dev/skills/majiayu000/claude-skill-registry/agent-customization"><img src="https://agentmods.dev/badge/skills/majiayu000/claude-skill-registry/agent-customization/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.

agentmods 80×15 button for agent-customization

Your own site · 80×15
<a href="https://agentmods.dev/skills/majiayu000/claude-skill-registry/agent-customization"><img src="https://agentmods.dev/badge/skills/majiayu000/claude-skill-registry/agent-customization.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 92 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 824 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found 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 5.1 $0.00092 $0.00824
Opus 5 $0.00046 $0.00412
Sonnet 5 $0.00018 $0.00165
Haiku 4.5 $0.00009 $0.00082

Measured 7d ago against content hash 2c0c9040c258, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

agent-customization 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 7d 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.

skills/agent/agent-customization/SKILL.md · 71 lines

How it starts

The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Customization

Decision Flow

Primitive When to Use
Workspace Instructions Always-on, applies everywhere in the project
File Instructions Explicit via applyTo patterns, or on-demand via description
MCP Integrates external systems, APIs, or data
Custom Agents Subagents for context isolation, or multi-stage workflows with tool restrictions
Prompts Single focused task with parameterized inputs
Skills On-demand workflow with bundled assets (scripts/templates)

Quick Reference

Consult the reference docs for templates, domain examples, advanced frontmatter options, asset organization, anti-patterns, and creation checklists.

Type File Location Key Field Reference
Workspace Instructions copilot-instructions.md, AGENTS.md .github/ or root N/A (always applies) Link
File Instructions *.instructions.md .github/instructions/ applyTo (explicit), description (on-demand) Link
Prompts *.prompt.md .github/prompts/ description (user-invoked) Link
Custom Agents *.agent.md .github/agents/ description (on-demand), infer (subagent) Link
Skills SKILL.md .github/skills/<name>/ description (on-demand) Link

User-level: {{USER_PROMPTS_FOLDER}}/ (*.prompt.md, *.instructions.md, *.agent.md; not skills) Customizations roam with user's settings sync

Creation Process

If you need to explore or validate patterns in the codebase, use a read-only subagent. If the ask-questions tool is available, use it to interview the user and clarify requirements.

Follow these steps when creating any customization file.

1. Determine Scope

Ask the user where they want the customization:

  • Workspace: For project-specific, team-shared customizations → .github/ folder
  • User profile: For personal, cross-workspace customizations → {{USER_PROMPTS_FOLDER}}/

Read the full file on GitHub · 71 lines

Files

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.

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. 7d ago First seen · 71 lines · 92 tokens per session scan A 2c0c9040c258

Subscribe to this mod's changes

agent-customization is a skill published in the GitHub repository majiayu000/claude-skill-registry (600 stars, last pushed today), licensed MIT. It adds 92 tokens to every session and 824 once invoked, about $0.0005 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 2026-09-03.

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