agent-development

agent-development is a skill for Claude Code from fazxes/Claude-code. It costs 80 tokens per session (2,484 once invoked), scanned A, original, no licence file.

A guide to designing coding-agent components that work as autonomous agents. It covers their structure, instructions, tools, and the conditions that make them start.

In plain words
What is it for?
It helps create agent definitions, write their instructions, choose tools, and set triggering rules.
Why use it?
It explains the decisions needed to make an agent understandable, correctly triggered, and useful within a plugin.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the plugin-dev plugin — 7 skills, 1 command, 3 agents shipped together

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/fazxes/claude-code/agent-development
Any agent
npx skills add fazxes/Claude-code --skill agent-development
Clone the repo
git clone --depth 1 https://github.com/fazxes/Claude-code

Made for: Claude Code.

Or install plugin-dev, the plugin that ships this one along with the rest of its 7 skills, 1 command, 3 agents.

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-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/fazxes/claude-code/agent-development.svg)](https://agentmods.dev/skills/fazxes/claude-code/agent-development)
Your own site
<a href="https://agentmods.dev/skills/fazxes/claude-code/agent-development"><img src="https://agentmods.dev/badge/skills/fazxes/claude-code/agent-development.svg" alt="Measured on agentmods" height="20"></a>
Per session 80 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,484 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00080 $0.02484
Opus 5 $0.00040 $0.01242
Sonnet 5 $0.00016 $0.00497
Haiku 4.5 $0.00008 $0.00248

Measured 3d ago against content hash 035ab8d53950, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

agent-development 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 3d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/validate-agent.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

stubs/downloads/official-plugins/marketplaces/claude-plugins-official/plugins/plugin-dev/skills/agent-development/SKILL.md · 416 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

6 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.

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. 3d ago First seen · 416 lines · 80 tokens per session scan A 035ab8d53950

Subscribe to this mod's changes

agent-development is a skill published in the GitHub repository fazxes/Claude-code (236 stars, last pushed 5mo ago), with no licence file. It adds 80 tokens to every session and 2,484 once invoked, about $0.0004 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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