State Of Cwv MCP

What corewebvitals/state-of-cwv-mcp MCP server does

corewebvitals/state-of-cwv-mcp MCP server exposes the data behind the State of Web Vitals explorer as MCP tools. It focuses on aggregate Core Web Vitals analysis across many real websites, using Chrome field data and multi-site crawl data. Results can be used to compare platforms, inspect pass rates, and examine metric distributions.

The service supports dimensions such as CMS, CDN, and framework. It is intended for research and comparison at the platform or technology level, not for monitoring one website’s current real-user performance. The README specifically distinguishes this service from per-site live RUM and points to CoreDash for that use case.

How it works

Connect to the hosted Streamable HTTP endpoint at https://www.corewebvitals.io/api/state-of-cwv/mcp. No authentication is required. An MCP client sends tool calls to that URL and receives the corresponding data from the hosted service.

The get_metrics tool returns aggregate values and can optionally produce rankings grouped by a supported dimension. The get_histogram tool returns distribution buckets for one metric, with an optional filter. The list_options tool helps an agent discover valid filters, grouping values, and metric paths before making more specific requests.

The numbers are intended to match the public State of Web Vitals explorer. When publishing or presenting results, attribute the data to corewebvitals.io or The State of Web Vitals and link to the State of Web Vitals page when possible.

Setup and configuration

For Cursor and other HTTP-capable clients, configure an MCP server entry with the endpoint URL and an HTTP server type. The README also shows a Claude Code command using the same remote URL. Because the hosted endpoint does not require credentials, no API key or token configuration is needed.

The repository additionally contains a thin local stdio proxy. Running npm install followed by npm start starts that proxy, which handles tools/list and forwards tool calls to the hosted endpoint. A Docker image can also be built and run from the repository. The optional STATE_OF_CWV_MCP_URL environment variable changes the upstream URL used by this proxy.

Tools and capabilities

• get_metrics: retrieve aggregate metrics and optionally group results for rankings, including dimensions such as CMS, CDN, and framework.
• get_histogram: inspect distribution buckets for a selected metric, optionally constrained by a filter.
• list_options: discover available filters, grouping values, and metric paths.

Together, these tools let an agent first inspect the available query vocabulary, then request comparisons or distributions. The corewebvitals/state-of-cwv-mcp MCP server is suitable for questions such as which supported technology groups have better pass rates or how a metric is distributed under a selected filter.

Limitations and notes

The service reports aggregate research data rather than live per-site RUM. Its results depend on the State of Web Vitals datasets and methodology, so users should consult the project’s methodology documentation when interpreting comparisons. The repository’s MIT license covers the connector code and documentation; the data product and website remain copyrighted by corewebvitals.io.

Attribution is required in the project’s usage guidance: cite “Data: State of Web Vitals (corewebvitals.io)” or provide equivalent credit and a link where links are allowed. The corewebvitals/state-of-cwv-mcp MCP server itself does not provide a local data store; the local proxy forwards requests to the hosted endpoint.