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 skills add veelenga/preview-skills --skill preview-markdowngit clone --depth 1 https://github.com/veelenga/preview-skillsWrote 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/veelenga/preview-skills/preview-markdown)<a href="https://agentmods.dev/skills/veelenga/preview-skills/preview-markdown"><img src="https://agentmods.dev/badge/skills/veelenga/preview-skills/preview-markdown/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/veelenga/preview-skills/preview-markdown"><img src="https://agentmods.dev/badge/skills/veelenga/preview-skills/preview-markdown.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 | $0.00020 | $0.01062 |
| Opus 5 | $0.00010 | $0.00531 |
| Sonnet 5 | $0.00004 | $0.00212 |
| Haiku 4.5 | $0.00002 | $0.00106 |
Grade A, and why
preview-markdown 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 9d 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 — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Preview Markdown Skill
GitHub-flavored Markdown viewer that generates beautiful HTML with syntax highlighting and automatic table of contents.
Agent Usage
When the user asks to preview a Markdown file, DO NOT build HTML manually. Use the Bash tool to execute this skill's run.sh script:
# Preview a file
./run.sh README.md
# Pipe content
cat docs.md | ./run.sh
The script handles all HTML generation and automatically opens the result in the browser. Do NOT open the file manually to avoid duplicate tabs.
Usage
# Preview a Markdown file
/preview-markdown README.md
# Pipe Markdown content (preferred for temporary content)
cat docs.md | /preview-markdown
echo "# Hello\n\nThis is **markdown**" | /preview-markdown
# With custom background color
/preview-markdown article.md --background "#ffffff"
Best Practice: For temporary or generated content, prefer piping over creating temporary files. This avoids cluttering your filesystem and the content is automatically cleaned up.
Options
The script works with sensible defaults but supports these flags for flexibility:
-o, --output PATH- Custom output path--no-browser- Skip browser, output file path only
Features
- GitHub-flavored Markdown rendering with full spec support
- Syntax highlighting for code blocks (100+ languages)
- Automatic TOC generation from headers
- Task lists with checkboxes
- Tables with formatting
- Images and links fully supported
- Math equations (LaTeX via KaTeX)
- Emoji support
- Footnotes and references
- Responsive design adapts to screen size
When to Use This Skill
Use this skill when the user wants to:
- Preview README or documentation files
- Read formatted Markdown documents
- Verify Markdown rendering before publishing
- Share formatted documentation
- Review pull request descriptions
Examples
Natural language requests:
- "preview this README"
- "show me the documentation"
- "open the markdown file"
- "visualize CONTRIBUTING.md"
- "let me see the formatted docs"
What ships with it
11 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.
- config.sh 1.2 KB runs code
- lib/browser-utils.sh 9.5 KB runs code
- lib/content-utils.sh 6.7 KB runs code
- lib/html-generator.sh 14 KB runs code
- run.sh 7.5 KB runs code
- templates/scripts/common-ui.js 5.1 KB runs code
- templates/scripts/markdown-renderer.js 9.3 KB runs code
- templates/scripts/utils.js 1.8 KB runs code
- templates/styles/common.css 1.6 KB
- templates/styles/layout.css 14 KB
- templates/styles/markdown.css 20 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.
- 9d ago First seen · 200 lines · 20 tokens per session scan A e476ab1e789d
preview-markdown is a skill published in the GitHub repository veelenga/preview-skills (8 stars, last pushed 28d ago), licensed MIT. It adds 20 tokens to every session and 1,062 once invoked, about $0.0001 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 2026-08-31.
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