How do I install the Alt Text Writer skill?

Run npx skillmds@latest add nanoodlecom/alt-text-writer in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Alt Text Writer safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Alt Text Writer?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Alt Text Writer free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Alt Text Writer?

nanoodlecom (@nanoodlecom) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Alt Text Writer by nanoodlecom — Agent Skill

Name: Alt Text Writer
Author: nanoodlecom

Alt Text Writer

Write accurate alt text and a figure caption for any image file — a vision model looks at the actual pixels and returns JSON with a 125-char alt string and a one-sentence caption. Use when filling in alt="" attributes, writing figure captions, or describing screenshots the agent cannot see.

nanoodlecom 3263308 2 files · 4.8 KB Updated Sep 17, 2026

File contents

Alt-text writer

Runs the bundled nanoodle workflow workflows/alt-text.noodle-graph.json against the NanoGPT API: an image input (Image) feeds a vision model whose question is assembled from two text nodes — the alt-text rules (Alt rules) and an optional house style guide (Style guide) — and the output (Alt text) is JSON with alt_125char and numbered_caption. Requires Node.js >= 20 and the nanoodle npm package (npx nanoodle fetches it).

Typical agent use: mid-PR, glob the repo's images, call this once per file, and write the returned alt_125char into the markup instead of guessing at pixels you cannot see.

API key

The run needs a NanoGPT API key. Use whichever is available:

NANOGPT_API_KEY already set in the environment — prefer this; no extra flags.
A .env file containing NANOGPT_API_KEY=... — pass --env-file <path> only when the key is not already in the environment. (With this CLI, --env-file overrides ambient NANOGPT_API_KEY.)

Never print the key.

Run

From this skill's directory (or prefix paths if running from elsewhere). Replace the image path with the real file (@path attaches a local file; an https:// URL also works):

npx nanoodle run workflows/alt-text.noodle-graph.json \
  --input "Image=@/path/to/image.jpg"

The output is text, so no --out directory is needed. For a machine-readable payload (outputs, cost, balance), the run summary JSON is always printed on stdout.

Optional overrides (both have baked-in defaults):

--input "Alt rules=<different output instructions>"
--input "Style guide=@docs/style-guide.md"

Inspect the interface anytime with:

npx nanoodle inspect workflows/alt-text.noodle-graph.json

Inputs

Key	Required	What to pass
`Image`	yes	Image file path (`@path`) or https URL
`Alt rules`	no (default baked in)	Alternative instructions for the metadata format
`Style guide`	no (default baked in)	House wording rules to apply

Outputs

Alt text is a text output: the CLI prints it on the Alt text: stderr line and includes it in the stdout JSON as outputs["Alt text"] — a JSON string with alt_125char and numbered_caption keys. Parse it from stdout.

Serve as an MCP tool

The same graph file works unchanged as a typed MCP tool — copy it into the folder nanoodle-mcp serves and the agent gets an alt-text tool with Image required:

mkdir -p ~/noodles && cp workflows/alt-text.noodle-graph.json ~/noodles/alt-text.json
claude mcp add nanoodle -- npx nanoodle-mcp --graphs ~/noodles

Cost

Each run costs a fraction of a cent (one gemini-2.5-flash-lite vision call). Cheap enough to fan out over a whole docs folder, but each call still spends real NanoGPT credit — the CLI prints the metered cost after every run.

---name: alt-text-writerdescription: Write accurate alt text and a figure caption for any image file — a vision model looks at the actual pixels and returns JSON with a 125-char alt string and a one-sentence caption. Use when filling in alt="" attributes, writing figure captions, or describing screenshots the agent cannot see.---# Alt-text writerRuns the bundled nanoodle workflow `workflows/alt-text.noodle-graph.json` against theNanoGPT API: an image input (`Image`) feeds a vision model whose question is assembled fromtwo text nodes — the alt-text rules (`Alt rules`) and an optional house style guide(`Style guide`) — and the output (`Alt text`) is JSON with `alt_125char` and`numbered_caption`. Requires Node.js >= 20 and the `nanoodle` npm package (`npx nanoodle`fetches it).Typical agent use: mid-PR, glob the repo's images, call this once per file, and write thereturned `alt_125char` into the markup instead of guessing at pixels you cannot see.## API keyThe run needs a NanoGPT API key. Use whichever is available:- `NANOGPT_API_KEY` already set in the environment — prefer this; no extra flags.- A `.env` file containing `NANOGPT_API_KEY=...` — pass `--env-file <path>` only when the key is not already in the environment. (With this CLI, `--env-file` overrides ambient `NANOGPT_API_KEY`.)Never print the key.## RunFrom this skill's directory (or prefix paths if running from elsewhere). Replace the imagepath with the real file (`@path` attaches a local file; an `https://` URL also works):```shnpx nanoodle run workflows/alt-text.noodle-graph.json \ --input "Image=@/path/to/image.jpg"```The output is text, so no `--out` directory is needed. For a machine-readable payload(outputs, cost, balance), the run summary JSON is always printed on stdout.Optional overrides (both have baked-in defaults):```sh--input "Alt rules=<different output instructions>"--input "Style guide=@docs/style-guide.md"```Inspect the interface anytime with:```shnpx nanoodle inspect workflows/alt-text.noodle-graph.json```## Inputs| Key | Required | What to pass ||-----|----------|--------------|| `Image` | yes | Image file path (`@path`) or https URL || `Alt rules` | no (default baked in) | Alternative instructions for the metadata format || `Style guide` | no (default baked in) | House wording rules to apply |## Outputs- `Alt text` is a **text** output: the CLI prints it on the `Alt text:` stderr line and includes it in the stdout JSON as `outputs["Alt text"]` — a JSON string with `alt_125char` and `numbered_caption` keys. Parse it from stdout.## Serve as an MCP toolThe same graph file works unchanged as a typed MCP tool — copy it into the folder`nanoodle-mcp` serves and the agent gets an `alt-text` tool with `Image` required:```shmkdir -p ~/noodles && cp workflows/alt-text.noodle-graph.json ~/noodles/alt-text.jsonclaude mcp add nanoodle -- npx nanoodle-mcp --graphs ~/noodles```## CostEach run costs a **fraction of a cent** (one `gemini-2.5-flash-lite` vision call). Cheapenough to fan out over a whole docs folder, but each call still spends real NanoGPTcredit — the CLI prints the metered cost after every run.

Frequently asked questions