Borrowing it
Nothing to install: this file belongs to akiojin/playfab-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/akiojin/playfab-mcp-server/main/.claude/skills/command-development/SKILL.mdgit clone --depth 1 https://github.com/akiojin/playfab-mcp-serverWrote 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/akiojin/playfab-mcp-server/command-development)<a href="https://agentmods.dev/skills/akiojin/playfab-mcp-server/command-development"><img src="https://agentmods.dev/badge/skills/akiojin/playfab-mcp-server/command-development/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/akiojin/playfab-mcp-server/command-development"><img src="https://agentmods.dev/badge/skills/akiojin/playfab-mcp-server/command-development.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00099 | $0.04284 |
| Opus 5.5 | $0.00040 | $0.01714 |
| Sonnet 5.5 | $0.00020 | $0.00857 |
| Haiku 4.5 | $0.00010 | $0.00428 |
Grade A, and why
Command 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 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.
This is a copy
92% identical to command-development — 78 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 — 835 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Command Development for Claude Code
Overview
Slash commands are frequently-used prompts defined as Markdown files that Claude executes during interactive sessions. Understanding command structure, frontmatter options, and dynamic features enables creating powerful, reusable workflows.
Key concepts:
- Markdown file format for commands
- YAML frontmatter for configuration
- Dynamic arguments and file references
- Bash execution for context
- Command organization and namespacing
Command Basics
What is a Slash Command?
A slash command is a Markdown file containing a prompt that Claude executes when invoked. Commands provide:
- Reusability: Define once, use repeatedly
- Consistency: Standardize common workflows
- Sharing: Distribute across team or projects
- Efficiency: Quick access to complex prompts
Critical: Commands are Instructions FOR Claude
Commands are written for agent consumption, not human consumption.
When a user invokes /command-name, the command content becomes Claude's instructions. Write commands as directives TO Claude about what to do, not as messages TO the user.
Correct approach (instructions for Claude):
Review this code for security vulnerabilities including:
- SQL injection
- XSS attacks
- Authentication issues
Provide specific line numbers and severity ratings.
Incorrect approach (messages to user):
This command will review your code for security issues.
You'll receive a report with vulnerability details.
The first example tells Claude what to do. The second tells the user what will happen but doesn't instruct Claude. Always use the first approach.
Command Locations
Project commands (shared with team):
- Location:
.claude/commands/ - Scope: Available in specific project
- Label: Shown as "(project)" in
/help - Use for: Team workflows, project-specific tasks
Personal commands (available everywhere):
- Location:
~/.claude/commands/ - Scope: Available in all projects
- Label: Shown as "(user)" in
/help - Use for: Personal workflows, cross-project utilities
What ships with it
10 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.
- examples/plugin-commands.md 14 KB
- examples/simple-commands.md 8.5 KB
- README.md 7.5 KB
- references/advanced-workflows.md 13 KB
- references/documentation-patterns.md 15 KB
- references/frontmatter-reference.md 8.9 KB
- references/interactive-commands.md 20 KB
- references/marketplace-considerations.md 16 KB
- references/plugin-features-reference.md 14 KB
- references/testing-strategies.md 14 KB
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 · 835 lines · 99 tokens per session scan A cf4372aa8f5e
Command Development is a skill published in the GitHub repository akiojin/playfab-mcp-server (3 stars, last pushed 5d ago), licensed MIT. It adds 99 tokens to every session and 4,284 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 92% identical to command-development, differing in 78 lines, and is treated as a copy.
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