Markdown Accessibility Skill
Reusable knowledge module for the
,
, and
agents and the
always-on instructions. Provides pattern libraries, severity scoring, fix templates, emoji translation maps, diagram description templates, and GitHub anchor generation rules for comprehensive markdown accessibility auditing across 9 domains.
Domains Covered
- Descriptive Links (WCAG 2.4.4) - Ambiguous link text, bare URLs, repeated identical text
- Image Alt Text (WCAG 1.1.1) - Missing, empty, filename-as-alt, generic placeholders
- Heading Hierarchy (WCAG 1.3.1 / 2.4.6) - Skipped levels, multiple H1s, bold-as-heading
- Table Accessibility (WCAG 1.3.1) - Missing descriptions, empty headers, layout tables
- Emoji (WCAG 1.3.3 / Cognitive) - Remove-all, remove-decorative, translate, or leave-unchanged modes
- Mermaid and ASCII Diagrams (WCAG 1.1.1 / 1.3.1) - Replace with accessible text + collapsible source
- Em-Dash / En-Dash Normalization (Cognitive) - Normalize to or leave unchanged
- Anchor Link Validation (WCAG 2.4.4) - Validate links against actual headings
- Plain Language and List Structure (Cognitive) - Emoji bullets, passive voice, sentence length
Severity Scoring
| Issue | Severity | WCAG | Auto-fix? |
|---|
| Image missing alt text | Critical | 1.1.1 (A) | No - needs visual judgment |
| Mermaid diagram with no text alternative | Critical | 1.1.1 (A) | Partial - simple diagrams auto-described; complex need human |
| ASCII diagram with no text description | Critical | 1.1.1 (A) | Partial - flag and wrap; description needs human or auto-gen |
| Broken anchor link | Serious | 2.4.4 (A) | No - confirm which end changes |
| Ambiguous link text ("here", "click here") | Serious | 2.4.4 (A) | Yes - rewrite using surrounding context |
| Skipped heading level | Serious | 1.3.1 (A) | Yes - interpolate missing level |
| Multiple H1s | Serious | 1.3.1 (A) | Yes - demote all but first |
| Emoji in heading | Moderate | Cognitive | Yes - remove or translate per preference |
| Consecutive emoji (2+) | Moderate | 1.3.3 (A) | Yes - remove sequence or translate |
| Emoji used as bullet | Moderate | 1.3.1 (A) | Yes - replace with |
| Em-dash in prose | Moderate | Cognitive | Yes - replace with |
| Table without preceding description | Moderate | 1.3.1 (A) | Yes - add one-sentence summary |
| Bold text used as heading | Minor | 2.4.6 (AA) | Yes - convert to appropriate heading |
| Bare URL in prose | Minor | 2.4.4 (A) | Yes - wrap with descriptive text |
| Emoji used for meaning, single inline | Minor | 1.3.3 (A) | Conditional - remove-all: yes; remove-decorative: flag; translate: translate |
Scoring Formula
text
File Score = 100 - (sum of weighted findings)
Critical: -15 pts each
Serious: - 7 pts each
Moderate: - 3 pts each
Minor: - 1 pt each
Floor: 0
Score Grades
| Score | Grade | Meaning |
|---|
| 90-100 | A | Excellent - accessible documentation |
| 75-89 | B | Good - minor issues |
| 50-74 | C | Needs Work - several barriers |
| 25-49 | D | Poor - significant barriers |
| 0-24 | F | Failing - critical AT barriers |
Emoji Handling Modes
The agent supports four modes configured during Phase 0:
| Mode | Description | Default? |
|---|
| Strip every emoji from prose, headings, and bullets | No |
| Remove emoji in headings, bullets, and consecutive sequences; flag single inline for review | Yes (default) |
| Replace known emoji with text; flag unknown for review | No |
| Do not flag or modify any emoji | No |
Emoji Translation Map
When using
mode, replace each emoji with the parenthesized English equivalent:
| Emoji | Translation | Emoji | Translation |
|---|
| 🚀 | (Launch) | ✅ | (Done) |
| ⚠️ | (Warning) | ❌ | (Error) |
| 📝 | (Note) | 💡 | (Tip) |
| 🔧 | (Configuration) | 📚 | (Documentation) |
| 🎯 | (Goal) | ✨ | (New) |
| 🔍 | (Search) | 🛠️ | (Tools) |
| 👋 | (Hello) | 🎉 | (Celebration) |
| ⭐ | (Featured) | 💬 | (Discussion) |
| 🏠 | (Home) | 📊 | (Data) |
| 🔒 | (Security) | 🌐 | (Web) |
| 📦 | (Package) | 🔗 | (Link) |
| 📋 | (Checklist) | 🏆 | (Achievement) |
| ⚡ | (Quick) | 👍 | (Approved) |
| 👎 | (Rejected) | 🐛 | (Bug) |
| 🤝 | (Collaboration) | 🎓 | (Learning) |
| 🔑 | (Key) | 📌 | (Pinned) |
| ℹ️ | (Info) | 🔄 | (Refresh) |
| ➕ | (Add) | ➖ | (Remove) |
| 💻 | (Code) | 🔔 | (Notification) |
| 📣 | (Announcement) | 🧪 | (Test) |
| 🎨 | (Design) | 🌟 | (Highlight) |
| 📈 | (Increase) | 📉 | (Decrease) |
| 🏗️ | (Build) | 🔐 | (Locked) |
| 📂 | (Folder) | 📁 | (Folder) |
| 🗂️ | (Category) | 🗃️ | (Archive) |
| ⚙️ | (Settings) | 🏁 | (Finish) |
| 🚧 | (In Progress) | 🚫 | (Not Allowed) |
| ✔️ | (Check) | ➡️ | (Next) |
| ⬆️ | (Up) | ⬇️ | (Down) |
For emoji not in this table: flag as
. Do not guess.
Emoji Detection Unicode Ranges
[\u{1F600}-\u{1F64F}] - Emoticons
[\u{1F300}-\u{1F5FF}] - Misc symbols and pictographs
[\u{1F680}-\u{1F6FF}] - Transport and map symbols
[\u{1F700}-\u{1F77F}] - Alchemical symbols
[\u{1F780}-\u{1F7FF}] - Geometric shapes extended
[\u{1F900}-\u{1F9FF}] - Supplemental symbols
[\u{1FA70}-\u{1FAFF}] - Symbols and pictographs extended
[\u{2600}-\u{26FF}] - Misc symbols
[\u{2700}-\u{27BF}] - Dingbats
[\u{1F1E0}-\u{1F1FF}] - Flags
[\u{FE00}-\u{FE0F}] - Variation selectors
Emoji-as-bullet pattern: list item where the first non-whitespace character is an emoji.
Pattern Library: Mermaid and ASCII Diagrams
Mermaid Detection
Lines matching
(with optional leading spaces/tabs).
Mermaid Description Templates
| Type | Description Template |
|---|
| / | "The following [direction] diagram shows: [list major nodes and connections from source]" |
| "The following sequence diagram shows the interaction between [participants]: [list each message in order]" |
| "The following class diagram shows [N] classes: [list class names, key properties, and relationships]" |
| "The following entity-relationship diagram shows [entities] with these relationships: [list relationships]" |
| "The following Gantt chart shows project tasks: [list section names and tasks with dates if available]" |
| "The following pie chart shows [title] with values: [list each label and percentage/value if available]" |
| "The following state diagram shows [N] states: [list state names and transition triggers]" |
| "The following mind map shows [root topic] with branches: [list top-level branch names]" |
| "The following timeline shows events: [list events in chronological order]" |
Auto-generate description for:
,
,
,
,
,
.
Flag for human review:
,
,
,
(complex enough to need human verification).
Mermaid Replacement Template
markdown
[Generated or user-provided text description - this is the primary accessible content]
<details>
<summary>Diagram source (Mermaid)</summary>
```mermaid
[original diagram source - unchanged]
</details>
```
ASCII Diagram Detection
ASCII art patterns: non-code-block lines (or unnamed code blocks) containing combinations of
,
,
,
,
,
,
,
,
,
forming a visual structure. Minimum 3 lines with consistent column alignment.
ASCII Diagram Replacement Template
markdown
[Generated or user-provided text description - this is the primary accessible content]
<details>
<summary>ASCII diagram</summary>
[original ASCII art - unchanged]
Pattern Library: Ambiguous Link Detection
Match these patterns (case-insensitive, trim whitespace):
Exact-match violations
here, click here, read more, learn more, more, more info,
link, details, info, go, see more, continue, start, download,
view, open, submit, this, that
Starts-with violations
click here to ..., read more about ..., learn more about ...,
here to ..., see more ...
URL-as-text pattern
Any link where visible text matches
or
Repeated identical text
Multiple
and
with same X but different URLs on the same page.
Safe patterns (do not flag)
- Badge links: at top of README
- Section self-references:
[Installation](#installation)
- Footer resource lists using the resource/tool name as text
Pattern Library: GitHub Anchor Generation
GitHub converts headings to anchor IDs using these rules:
- Lowercase entire string
- Remove all characters except: letters (a-z), digits (0-9), spaces, hyphens
- Replace spaces with hyphens
- Remove leading and trailing hyphens
Examples
| Heading | Anchor |
|---|
| |
| |
| |
| |
| |
## FAQ (Frequently Asked Questions)
| #faq-frequently-asked-questions
|
| (emoji becomes empty, may vary) |
For headings containing emoji: GitHub strips the emoji character and generates an anchor from the remaining text. Anchors referencing emoji-containing headings are fragile and should be flagged.
Pattern Library: Emoji Detection
Unicode emoji ranges for regex detection:
[\u{1F600}-\u{1F64F}] # Emoticons
[\u{1F300}-\u{1F5FF}] # Misc symbols and pictographs
[\u{1F680}-\u{1F6FF}] # Transport and map symbols
[\u{1F700}-\u{1F77F}] # Alchemical symbols
[\u{1F780}-\u{1F7FF}] # Geometric shapes extended
[\u{1F800}-\u{1F8FF}] # Supplemental arrows-C
[\u{1F900}-\u{1F9FF}] # Supplemental symbols and pictographs
[\u{1FA00}-\u{1FA6F}] # Chess symbols
[\u{1FA70}-\u{1FAFF}] # Symbols and pictographs extended-A
[\u{2600}-\u{26FF}] # Misc symbols
[\u{2700}-\u{27BF}] # Dingbats
[\u{FE00}-\u{FE0F}] # Variation selectors
[\u{1F1E0}-\u{1F1FF}] # Flags
Emoji-as-bullet pattern: List item where first non-whitespace character is an emoji.
Pattern Library: Em-Dash and En-Dash
Detection patterns:
— Unicode em-dash (U+2014)
– Unicode en-dash (U+2013)
--- Three hyphens in prose (not on its own line as HR)
-- Two hyphens in prose (used as em-dash substitute)
Safe to skip (do not modify):
- Line containing only (horizontal rule)
- Content inside code fences
- Content inside backtick inline code
- YAML front matter block
- HTML comment blocks
Replacement:
(space + hyphen + space)
En-dash in numeric ranges:
->
Pattern Library: Mermaid Diagrams
Detection: Lines matching
(with optional leading spaces/tabs)
Diagram types and description guidance:
| Type | Description Template |
|---|
| "The following diagram shows a [direction] flowchart: [list major nodes and connections]" |
| "The following sequence diagram shows the interaction between [participants]: [list message exchanges]" |
| "The following class diagram shows [N] classes: [list class names and key relationships]" |
| "The following entity-relationship diagram shows [entities] and their relationships: [list relationships]" |
| "The following Gantt chart shows project phases: [list tasks and timeframes]" |
| "The following pie chart shows [title] with values: [list segment names and values if available]" |
| "The following state diagram shows [N] states and transitions: [list states and transition triggers]" |
Wrapping template:
markdown
[Generated or user-provided text description]
<details>
<summary>Diagram source (Mermaid)</summary>
```mermaid
[original diagram source]
</details>
```
Fix Templates
Ambiguous link fix
markdown
# Before
For more information, see [here](https://example.com/guide).
# After
For more information, see the [installation guide](https://example.com/guide).
Emoji bullet fix
markdown
# Before
- 🚀 Deploy to production
- ✅ Run tests
# After
- Deploy to production
- Run tests
Emoji heading fix
markdown
# Before
## 🔧 Configuration
# After
## Configuration
Em-dash fix
markdown
# Before
The agent—when invoked—will scan all files.
# After
The agent - when invoked - will scan all files.
Table description fix
markdown
# Before
|------|----------|----------|
# After
The following table lists rules with their severity level and whether they can be fixed automatically.
| Rule | Severity | Auto-fix |
|------|----------|----------|
Broken anchor fix
markdown
# Before (broken)
See [Installation](#instalation) for setup steps.
# Heading in file
## Installation
# After (corrected)
See [Installation](#installation) for setup steps.
Markdownlint Rules Reference
| Rule | Name | Accessibility Relevance |
|---|
| MD001 | heading-increment | Heading hierarchy (WCAG 1.3.1) |
| MD022 | blanks-around-headings | Parsing reliability |
| MD024 | no-duplicate-heading | Unique section identity (WCAG 2.4.6) |
| MD025 | single-title / single-h1 | One H1 per document |
| MD033 | no-inline-html | May hide structure from parsers |
| MD034 | no-bare-urls | Ambiguous links (WCAG 2.4.4) |
| MD041 | first-line-heading | Document structure |
| MD055 | table-pipe-style | Table parsing consistency |
| MD056 | table-column-count | Table structural integrity |
Command:
npx --yes markdownlint-cli2 <filepath>