AltText.ai

AltText.ai MCP Server

An MCP server that lets AI assistants generate alt text, manage image libraries, and queue alt text generation for web page images using the AltText.ai API.

Works with Claude Desktop, Claude Code, Cursor, Windsurf, and any MCP-compatible client.

Verify this package

This server runs npx -y @alttext_ai/alttext-mcp, which downloads and executes code with your API key in its environment. That's worth a moment of verification before you install — by you or by an AI agent doing the setup. Everything below should match:

Signal	Value
npm package	@alttext_ai/alttext-mcp
Source repository	github.com/alttextai/alttext-mcp
Publisher	AltText.ai
Provenance	Published from this repo's CI with npm provenance — npm shows a verified build badge linking the package to this exact commit

The npm scope is @alttext_ai (with an underscore), while the GitHub org is alttextai (no underscore). This is intentional, not a typosquat: the @alttextai npm scope was already taken, so we publish under @alttext_ai. The two names refer to the same official AltText.ai package.

To cryptographically verify the published package was built by this repo's CI — not just trust the metadata — run:

npm audit signatures

from a project where the package is installed. This validates the registry signature and the npm provenance attestation, which links the tarball to a specific commit and GitHub Actions build. A counterfeit package can forge repository.url and other metadata, but it cannot forge the provenance attestation — so this is the check that actually matters.

(For a quick, weaker cross-reference of the claimed source you can run npm view @alttext_ai/alttext-mcp repository.url, but note that field is publisher-controlled metadata and proves nothing on its own.)

Pinning a version

The setup snippet uses npx -y @alttext_ai/alttext-mcp, which always resolves to the latest published version and re-runs it on every launch. That keeps you current, but it also means a future release runs automatically without review. If you want a reproducible, audited install, pin a specific version:

"args": ["-y", "@alttext_ai/alttext-mcp@1.0.5"]

Run npm audit signatures against the pinned version, and bump it deliberately when you're ready to take a new release.

Setup

Requirements: Node.js 22+ and an AltText.ai API key

Add the server to your MCP client configuration:

{
  "mcpServers": {
    "alttext-ai": {
      "command": "npx",
      "args": ["-y", "@alttext_ai/alttext-mcp"],
      "env": {
        "ALTTEXT_API_KEY": "your-api-key"
      }
    }
  }
}

Where to add this:

Client	Config file
Claude Desktop	claude_desktop_config.json
Claude Code	.mcp.json in your project root
Cursor	MCP settings in the Cursor preferences
Windsurf	MCP settings in the Windsurf preferences

Tools

Account Management

Tool	Description
get_account	Check your credit balance, usage, and account settings.
update_account	Update account name, webhook URL, or notification email.

Generate Alt Text

Tool	Description
generate_alt_text	Generate alt text for an image URL. Supports multilingual output, custom prompts, keywords, and character limits. Uses account credits.
generate_alt_text_from_file	Generate alt text from a local image file. Automatically base64-encodes and uploads. Uses account credits.
translate_image	Add alt text in a new language for an existing image (by asset_id). Uses account credits.

Manage Image Library

Tool	Description
list_images	List images in your library with pagination.
search_images	Search your image library by alt text content.
get_image	Get details for a specific image by asset ID.
update_image	Update alt text, tags, or metadata for an image.
delete_image	Delete an image from your library.

Bulk Operations

Tool	Description
bulk_create	Bulk generate alt text from a CSV file with image URLs and optional metadata.
scrape_page	Scan a web page, find images missing alt text, and queue generation. Results are async -- use list_images to check progress.

Effects and processing

This package uses stdio and runs on the machine launching the MCP client. Image and CSV paths refer to that machine; selected file contents are uploaded to AltText.ai.

Generation and translation use your account credits. Additional languages and image conversion can increase the total. Check get_account before paid work. Generation can overwrite existing alt text when requested; updates replace supplied fields and deletion removes the image from the library.

CSV imports and page scraping queue background processing. An accepted request does not mean generation has finished; inspect the image library and any configured completion notifications. Tool annotations describe effects for clients; they do not enforce confirmation.

Example Prompts

Once configured, just ask your AI assistant:

Account & Credits

• "How many credits do I have left?"
• "Update my webhook URL to https://example.com/webhook"

Generate Alt Text

• "Generate alt text for https://example.com/photo.jpg"
• "Generate alt text for this image" (with local file)
• "Generate alt text in French and Spanish for this image"
• "Translate image abc123 to German"

Manage Library

• "Search my images for 'product photo'"
• "List my images"
• "Get details for image abc123"
• "Update the alt text for asset abc123"
• "Delete image xyz789"

Bulk Operations

• "Generate alt text for images missing it on https://example.com"
• "Process this CSV file of image URLs" (bulk_create)

Environment Variables

Variable	Required	Description
ALTTEXT_API_KEY	Yes	Your AltText.ai API key
ALTTEXT_API_BASE_URL	No	Override the API base URL (default: https://alttext.ai/api/v1)

Development

npm install
npm run build
npm test
npm run lint

Tests use mocked fetch calls -- no API key or network access needed.

Hosted deployments must rate-limit POST /register at a trusted edge using the verified client address. The Node service deliberately ignores forwarded client-address headers because accepting them without an authenticated proxy boundary would let callers spoof the rate-limit identity.

The production container and required settings are documented in docs/deployment.md.

License

MIT

Registry publishing

server.json describes the stdio npm package. Its name matches mcpName in package.json; both versions must match the release being submitted. Publish and verify that exact npm version before running mcp-publisher publish. Registry acceptance and directory approval are separate from an npm release.