markdown-preview

markdown-preview is a skill for Claude Code from rp1-run/rp1. It costs 30 tokens per session (2,717 once invoked), scanned A, original, Apache-2.0.

A document-preview tool that turns Markdown, plain text, and Mermaid diagrams into styled HTML pages you can view in a web browser. Mermaid is a text format for diagrams such as flowcharts and sequence diagrams.

In plain words
What is it for?
Use it to preview documentation, render diagrams, display highlighted code, or create browser-viewable reports.
Why use it?
It lets you check how documentation and diagrams will look without manually formatting them or setting up a preview page.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the rp1-base plugin — 20 skills, 17 agents, 1 hook shipped together

Good fit Use it to preview documentation, render diagrams, display highlighted code, or create…

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Install with agentmods
npx agentmods add skills/rp1-run/rp1/markdown-preview
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 rp1-run/rp1 --skill markdown-preview
Clone the repo
git clone --depth 1 https://github.com/rp1-run/rp1

Made for: Claude Code.

Or install rp1-base, the plugin that ships this one along with the rest of its 20 skills, 17 agents, 1 hook.

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 markdown-preview

README.md
[![agentmods](https://agentmods.dev/badge/skills/rp1-run/rp1/markdown-preview.svg)](https://agentmods.dev/skills/rp1-run/rp1/markdown-preview)
Your own site
<a href="https://agentmods.dev/skills/rp1-run/rp1/markdown-preview"><img src="https://agentmods.dev/badge/skills/rp1-run/rp1/markdown-preview.svg" alt="Measured on agentmods" height="20"></a>
Per session 30 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,717 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.
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 $0.00030 $0.02717
Opus 5 $0.00015 $0.01358
Sonnet 5 $0.00006 $0.00543
Haiku 4.5 $0.00003 $0.00272

Measured 7d ago against content hash 4b34b0d790d6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

markdown-preview 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.

plugins/base/skills/markdown-preview/SKILL.md · 357 lines

How it starts

The opening of the file, as written. The whole thing — 357 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Markdown Preview Generator — Browser-Ready HTML from Markdown

Generate self-contained HTML files from markdown content and automatically open them in the user's default browser.

What This Skill Does

  • Accepts GitHub-flavored markdown, plain text, and Mermaid diagrams
  • Validates all Mermaid diagrams in document at once (single validation pass)
  • Generates single-page HTML with embedded libraries (marked.js, Prism.js, Mermaid.js)
  • Applies professional styling (GitHub-style, dark mode, or minimal)
  • Saves HTML to system temp directory with unique filename
  • Auto-opens preview in default browser (cross-platform: macOS, Linux, Windows)
  • Returns file path and execution status

When to Use

Use this skill when you need to:

  • Preview markdown documentation in a browser
  • Visualize Mermaid diagrams with proper rendering
  • Generate formatted HTML reports for users
  • Display code blocks with syntax highlighting
  • Create professional previews of generated content

Trigger scenarios: markdown preview, HTML generation, browser preview, document visualization, diagram rendering.

Parameters

Parameter Type Required Default Description
content string Yes - Markdown, plain text, or Mermaid content to render
title string No "Markdown Preview" HTML page title
theme string No "github" Template theme: "github", "dark", or "minimal"

Workflow

1. Parse Input Content

Extract content from agent context or parameters. The skill expects markdown content as a string input.

2. Validate All Mermaid Diagrams (Single Pass)

Efficient Validation Strategy:

Instead of validating each diagram individually, validate the entire markdown document at once:

  1. Write markdown to temp file:

    TEMP_MD=$(mktemp /tmp/markdown-preview.XXXXXX.md)
    echo "$CONTENT" > "$TEMP_MD"
    
  2. Validate all diagrams in one pass:

    rp1 agent-tools mmd-validate "$TEMP_MD"
    EXIT_CODE=$?
    

Read the full file on GitHub · 357 lines

Files

What ships with it

2 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. 7d ago First seen · 357 lines · 30 tokens per session scan A 4b34b0d790d6

Subscribe to this mod's changes

markdown-preview is a skill published in the GitHub repository rp1-run/rp1 (38 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 30 tokens to every session and 2,717 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.