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Accessible Alt Text Writer

Generates and audits accessible alt text for figures in R package (pkgdown) sites and Quarto documents by reading the plotting code and surrounding prose.

Content & WritingIntermediate★ 520⑂ 53AI score 7/10Last updated: Sep 18, 2026

What it does

  • Detects the project type by checking for _pkgdown.yml, then loads the matching reference guide (pkgdown or Quarto).
  • Uses the chart-generating code (aesthetic mappings, color encodings, facet counts, fitted curves) and the surrounding text to extract precise, verifiable details instead of guessing from a rendered image.
  • Writes alt text with Amy Cesal's three-part formula: chart type → data description → key insight.
  • Reads the caption (fig-cap, fig.cap) first so alt text complements rather than duplicates it.
  • Ships include/exclude rules, a length table by complexity, per-chart-type templates, and a quality checklist.

Who it's for

  • R package maintainers publishing ggplot2-heavy pkgdown documentation.
  • Data analysts and authors writing Quarto (.qmd) reports, books, or blogs.
  • Teams running accessibility (WCAG) audits on technical documentation figures.

Example uses

  1. "Add fig.alt to every figure in this package's vignettes" — it reads each chunk and applies the right template.
  2. "Improve the alt text for fig-normalization in chapter-03.qmd" — trims caption duplication and foregrounds the insight.
  3. "Audit our existing alt text" — flags missing axis variables, redundant "Image of…" openers, and over-long descriptions.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/posit-dev/skills/HEAD/alt-text/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the alt-text folder from the GitHub repo posit-dev/skills into my ~/.claude/skills/alt-text/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/posit-dev/skills.git /tmp/posit-skills && mkdir -p ~/.claude/skills && cp -r /tmp/posit-skills/alt-text ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal.
  2. Clone the repo: git clone https://github.com/posit-dev/skills.git
  3. Create the skills folder: mkdir -p ~/.claude/skills
  4. Copy the whole skill directory (the references/ folder must come along): cp -r skills/alt-text ~/.claude/skills/
  5. Start claude from inside your R package or Quarto project directory.
  6. Ask something like "add alt text to the figures in this document" and the skill activates automatically.
View source on GitHub ↗License: MIT