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/val-town/plugins/create-skillnpx skills add val-town/plugins --skill create-skillgit clone --depth 1 https://github.com/val-town/pluginsWhat 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 | $0.00038 | $0.00580 |
| Opus 5 | $0.00019 | $0.00290 |
| Sonnet 5 | $0.00008 | $0.00116 |
| Haiku 4.5 | $0.00004 | $0.00058 |
Grade A, and why
create-skill 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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skills in Val Town instruct Townie and other AI agents using the Val Town MCP server how to write idiomatic vals that respect a user's preferences and knowledge.
In any val, a user can create a /skills/<name>/SKILL.md file, e.g. /skills/design/SKILL.md.
Townie and the Val Town MCP server index skills with that directory/file structure across all of a user's vals.
A user may choose to centralize their skills in one val or co-locate skills across multiple vals.
Frontmatter
A skill markdown file must have frontmatter:
name: kebab-case name of the skill; contains lowercase letters, numbers, and hyphensdescription: helps the agent decide when the skill is relevant. A good skill description is critical for agent discoverytriggers: (optional) is a list of keywords to tip off the agent
The description and triggers fields enable skill discovery, i.e. tells the user's AI agent (e.g. Claude Code, Codex, Cursor) when to use it.
The more specific the better, including key terms that should trigger use (which can also be enumerated in triggers).
Skills without frontmatter will be silently skipped, so Townie/MCP will not be able to access them.
Best practices
The Claude Platform Docs offer skill authoring best practices, including:
- Be concise. The context window is a public good
- Always write in third person
- Default assumption: AI agents are already very smart
- Be as specific as possible (e.g. code is better than plain english where possible)
- Improve skills based on usage and testing
Example
---
name: design
description: Use when styling a val's UI. Use for frontend vals that return JSX or HTML
triggers: [css, styling, layout, theme]
---
- Use `.css` files, avoid inline styles and Tailwind
- Locate React components in a `/components` directory, one component per file
- Use a sans-serif web-native font stack, no external fonts
- ...
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.
- 2d ago First seen · 54 lines · 38 tokens per session scan A faaa88bfddd2
create-skill is a skill published in the GitHub repository val-town/plugins (10 stars, last pushed 3d ago), licensed MIT. It adds 38 tokens to every session and 580 once invoked, about $0.0002 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 2026-08-30.
Other skills, from other repositories
weekly-digests
Generate a serial week-by-week narrative digest of a project's full claude-mem timeline. Splits the timeline into per-ISO-week files, then runs one consecutive subagent per week — each receiving the prior week's carry-forward block — to produce one chapter per ISO week of data. Use when asked for "weekly digests"…
agentmail
Use when an agent needs AgentMail CLI email inboxes.
skill-template
Template for creating new Agent Skills for context engineering. Use this template when adding new skills to the collection.
Agent Development
This skill should be used when the user asks to "create an agent", "add an agent", "write a subagent", "agent frontmatter", "when to use description", "agent examples", "agent tools", "agent colors", "autonomous agent", or needs guidance on agent structure, system prompts, triggering conditions, or agent development…
skill-creator
Scaffold a new yoyo skill when a human or community issue asks for one ("add a skill for X", "create a skill that does Y"). Generates correct frontmatter, validates, writes to disk.
subagent-delegation
Canonical protocol for delegating GSD work to native Antigravity subagents — when to delegate, how to invoke, workspace isolation modes, and the inline fallback for older IDE versions.