Development

Responsive Picture / srcset Art Direction Builder

Build complete <picture> markup with art-directed crops: per-breakpoint <source media> elements, 1x/2x density candidates or {w}-template width descriptors, optional AVIF/WebP format layers, sizes handling, CLS-safe width/height, plus HTML and JSX flavors with spec-based lint notes.

html· HTML resultOpen tool

Quick start

Call this tool from your code in three languages.

cURL

# 1) Request a presigned URL → returns { uploadUrl, storageKey }
curl -X POST 'https://api.elysiatools.com/api/upload/presign/responsive-picture-srcset-art-direction-builder' \
  -H 'Content-Type: application/json' \
  -d '{"filename":"variantImages.ext","contentType":"application/octet-stream","size":12345}'

# 2) PUT the file bytes directly to the presigned uploadUrl
curl -X PUT '<presigned uploadUrl>' \
  --data-binary @/path/to/file.ext

# 3) Call the tool, passing the returned storageKey for each file field
curl -X POST 'https://api.elysiatools.com/en/api/tools/responsive-picture-srcset-art-direction-builder' \
  -F 'sources=768 /img/hero-mid.jpg
1280 /img/hero-wide.jpg' \
  -F 'variantImages=uploads/2026/01/01/your-tool-1700000000000-abc123.ext' \
  -F 'descriptorMode=density' \
  -F 'densities=1x,2x' \
  -F 'sizesAttr=(min-width: 1024px) 960px, 100vw' \
  -F 'fallbackUrl=/img/hero-mobile.jpg' \
  -F 'altText=Fresh sourdough loaves on a marble counter' \
  -F 'formatLayer=none' \
  -F 'flavor=html' \
  -F 'lazyAttrs=true'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/responsive-picture-srcset-art-direction-builder

Parameters

Name	Type	Required	Description
sources	textarea	No	—
variantImages	fileupload required	No	—
descriptorMode	select	Yes	—
densities	text	No	—
sizesAttr	text	No	—
fallbackUrl	text	No	—
altText	text	No	—
formatLayer	select	Yes	—
flavor	select	Yes	—
lazyAttrs	checkbox	No	—

File-type parameters must be uploaded first via POST /upload/responsive-picture-srcset-art-direction-builder, then the returned filePath is passed to the corresponding file field.

Response format

HTML result

JSON

{
  "result": "<div>Processed HTML content</div>",
  "error": "Error message (optional)",
  "message": "Notification message (optional)",
  "metadata": {
    "key": "value"
  }
}

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-responsive-picture-srcset-art-direction-builder": {
      "name": "responsive-picture-srcset-art-direction-builder",
      "description": "Build complete <picture> markup with art-directed crops: per-breakpoint <source media> elements, 1x/2x density candidates or {w}-template width descriptors, optional AVIF/WebP format layers, sizes handling, CLS-safe width/height, plus HTML and JSX flavors with spec-based lint notes.",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=responsive-picture-srcset-art-direction-builder",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "responsive-picture-srcset-art-direction-builder",
    "arguments": {
  "sources": "768 /img/hero-mid.jpg\n1280 /img/hero-wide.jpg",
  "variantImages": "https://example.com/file.ext",
  "descriptorMode": "density",
  "densities": "1x,2x",
  "sizesAttr": "(min-width: 1024px) 960px, 100vw",
  "fallbackUrl": "/img/hero-mobile.jpg",
  "altText": "Fresh sourdough loaves on a marble counter",
  "formatLayer": "none",
  "flavor": "html",
  "lazyAttrs": true
}
  }
}

Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

File parameters accept a public file URL only (https://…). Local paths, data: URIs, and Base64 strings are not supported.

Questions or issues? Contact [email protected]