markdown-linter

markdown-linter is a skill for Claude Code, Codex from lyupro/skillforge-mcp. It costs 23 tokens per session (362 once invoked), scanned A, original, MIT.

A checker for Markdown files that reports common formatting and structure problems, such as skipped heading levels, trailing spaces, and missing image descriptions. Markdown is plain text commonly used for documentation and README files.

In plain words
What is it for?
Checking headings, whitespace, indentation, image alt text, links, and list markers in a .md file.
Why use it?
It finds consistency and accessibility issues before a Markdown document is published or reviewed. The reports include the line, column, severity, rule, and message for each finding.

Skill for Claude CodeCodex

Part of the skillforge plugin — 10 skills, 1 MCP server 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/lyupro/skillforge-mcp/markdown-linter
Any agent
npx skills add lyupro/skillforge-mcp --skill markdown-linter
Clone the repo
git clone --depth 1 https://github.com/lyupro/skillforge-mcp

Made for: Claude Code, Codex.

Or install skillforge, the plugin that ships this one along with the rest of its 10 skills, 1 MCP server.

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-linter

README.md
[![agentmods](https://agentmods.dev/badge/skills/lyupro/skillforge-mcp/markdown-linter.svg)](https://agentmods.dev/skills/lyupro/skillforge-mcp/markdown-linter)
Your own site
<a href="https://agentmods.dev/skills/lyupro/skillforge-mcp/markdown-linter"><img src="https://agentmods.dev/badge/skills/lyupro/skillforge-mcp/markdown-linter.svg" alt="Measured on agentmods" height="20"></a>
Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 362 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00023 $0.00362
Opus 5 $0.00012 $0.00181
Sonnet 5 $0.00005 $0.00072
Haiku 4.5 $0.00002 $0.00036

Measured 4d ago against content hash b380a8d22de5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

markdown-linter 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 4d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/main.py), 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.

skills/markdown-linter/SKILL.md · 36 lines

What it actually says

This is a script-strategy skill. The script in scripts/main.py reads the Markdown file path from SKILLFORGE_INPUT, runs a built-in linter against it (no third-party dependencies — only the Python standard library), and prints findings to stdout, one per line.

Output format (one finding per line):

<line_number>:<column>:<severity>:<rule>:<message>

Severities: error, warning, info. Rules:

  • heading-order — H2 follows H1, H3 follows H2, no skipped levels.
  • trailing-whitespace — lines ending in space or tab.
  • tab-indent — tabs used for indent (Markdown prefers spaces).
  • missing-alt![](url) with empty alt text.
  • bare-url — http(s) URL not wrapped in <...> or [text](url).
  • mixed-list-marker — list switches between -, *, + inside the same block.

When the file does not exist or SKILLFORGE_INPUT is empty, the script prints 0:0:error:io:no input file and exits 0.

Prerequisites:

  • config.security.allowScripts: true.
  • python3 on the host's resolved PATH.
  • SKILLFORGE_INPUT set to the absolute path of the .md file to lint.
Files

What ships with it

1 file 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. 4d ago First seen · 36 lines · 23 tokens per session scan A b380a8d22de5

Subscribe to this mod's changes

markdown-linter is a skill published in the GitHub repository lyupro/skillforge-mcp (1 stars, last pushed 20d ago), licensed MIT. It adds 23 tokens to every session and 362 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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