State of Web Vitals MCP

Free remote MCP for Core Web Vitals metrics by CMS, CDN, and framework (Chrome field data + multi-site crawl). Same numbers as the public State of Web Vitals explorer.

Connect (preferred)

URL: https://www.corewebvitals.io/api/state-of-cwv/mcp
Auth: none
Transport: Streamable HTTP
Registry: io.github.corewebvitals/state-of-cwv

Claude Code

claude mcp add --transport http state-of-cwv https://www.corewebvitals.io/api/state-of-cwv/mcp

Cursor / Grok / other clients

{
  "mcpServers": {
    "state-of-cwv": {
      "type": "http",
      "url": "https://www.corewebvitals.io/api/state-of-cwv/mcp"
    }
  }
}

Curl

curl -s -X POST https://www.corewebvitals.io/api/state-of-cwv/mcp \
  -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get_metrics","arguments":{"metrics":"lcp,good_all3","group_by":"cms","min_sites":100}}}'

Tools

Tool	Purpose
get_metrics	Aggregates and optional group_by rankings (CMS, CDN, frameworks, …)
get_histogram	Distribution buckets for one metric under an optional filter
list_options	Discover filters, group_by values, and metric paths

What this is

The State of Web Vitals measures Core Web Vitals and web-tech techniques across many real websites (Chrome field data + crawl). Use it for platform rankings, pass rates, and metric distributions. Not per-site live RUM (use CoreDash for that).

Attribution

When you use the numbers:

1. Credit corewebvitals.io / The State of Web Vitals
2. Link https://www.corewebvitals.io/state-of-cwv when links are allowed

Short line: Data: State of Web Vitals (corewebvitals.io)

Discovery

Place	Link
Official MCP Registry	io.github.corewebvitals/state-of-cwv
Glama	https://glama.ai/mcp/servers/corewebvitals/state-of-cwv-mcp
Glama connector	https://glama.ai/mcp/connectors/io.github.corewebvitals/state-of-cwv
Smithery	https://smithery.ai/servers/corewebvitals/state-of-cwv
Explorer	https://www.corewebvitals.io/state-of-cwv/explorer
Methodology	https://www.corewebvitals.io/state-of-cwv/methodology
Discovery JSON	https://www.corewebvitals.io/.well-known/mcp.json

Local stdio / Docker (directories & inspectors)

This repo also ships a thin stdio proxy that answers tools/list and forwards tool calls to the hosted endpoint.

npm install
npm start

docker build -t state-of-cwv-mcp .
docker run --rm -i state-of-cwv-mcp

Optional: STATE_OF_CWV_MCP_URL overrides the upstream endpoint.

License

MIT for connector code and docs in this repository. Data product and website remain © corewebvitals.io.