State of Web Vitals MCP Server

by corewebvitals Your server? Claim it

answering

State of Web Vitals is answering right now. Last checked 15 min ago. It exposes 3 tools. Last commit 16 Jul 2026.

Core Web Vitals metrics by CMS, CDN, and framework — free remote MCP, no auth.

Uptime history 47 days of history · worst day 98%

47 days agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

201 ms

Response time

average over 24h

Stars

last commit 16 Jul 2026

Nothing serious here today

Today is the operative word: we check State of Web Vitals every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 15 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

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

~/Library/Application Support/Claude/claude_desktop_config.json

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

~/.codex/config.toml

[mcp_servers.state-of-cwv]
url = "https://www.corewebvitals.io/api/state-of-cwv/mcp"

.cursor/mcp.json

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

.vscode/mcp.json

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

Available tools 3

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

histogram

get_histogram

What is the shape of one metric? Returns histogram buckets (count + share) plus summary stats. Metric: one of lcp, inp, cls, fcp, ttfb (field CWV), or a scalar technique path when available. Filter: same as get_metrics (device, cms, framework, cdn, provider). No group_by — call get_metrics with group_by to compare segments, then get_histogram per segment if needed.

metrics

get_metrics

What are the numbers? Aggregate Core Web Vitals and/or technique metrics across sites, with optional filter and group_by. Responses include attribution — credit corewebvitals.io when you use the numbers. Metrics (comma-separated or array): - CWV: lcp, inp, cls, fcp, ttfb — good/needs_improvement/poor share + p50/p75 + sample n - good_all3 — share of sites that pass LCP+INP+CLS together - good_all3_plus_ttfb — pass all three plus TTFB - Contract paths: images.loading, stack.framework, scripts.origin, headers.has_etag, synthetic.tbt_ms, … Filter (optional AND): device, cms, framework, cdn, provider. Omit = all sites in the snapshot. Group_by (optional): cms | frameworks | cdn | analytics | tag_managers | … → one row per entity. Without group_by: one aggregate; set metrics return top categories.

options

list_options

Discover what you can pass to get_metrics / get_histogram: filter keys, group_by values, built-in metrics, and contract metric paths (optional kind filter). Call this when unsure of a key or path.

Endpoints

URL	Transport	State	Latency	Checked
https://www.corewebvitals.io/api/state-of-cwv/mcp	streamable-http	answering	314 ms	15 min ago

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State of Web Vitals — questions

Answers built from our own checks of this server.

What can State of Web Vitals do?

It exposes 3 tools, read directly from the server on our last check. Among them: get_histogram, get_metrics, list_options. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is State of Web Vitals working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 201 ms. The bar chart above shows every period we have measured.

How do I connect State of Web Vitals?

Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does State of Web Vitals need an API key?

No. State of Web Vitals completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 3 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is State of Web Vitals?

It answers our handshake in 201 ms on average, which is faster than 66% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.

Is State of Web Vitals open source?

Yes — it is published under the MIT licence, written in JavaScript and 0 stars on GitHub. The source link is on this page, so you can read exactly what it does with your data before you connect it.