WebPerf Snippets MCP

An MCP server that exposes 56 tested JavaScript snippets for measuring and debugging web performance. It allows AI agents to run these snippets on headless Chromium to obtain structured data for Core Web Vitals, loading metrics, and interaction analysis, ensuring deterministic audits.

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Package and access

Local package with source-attributed installation metadata. Koskamo does not execute packages during review.

Community listingLocal stdioSource reviewed; not executedPublished by nucliweb

Vendor documentation

What you can do with it

Measure Core Web Vitals like LCP, CLS, and INP
Debug render-blocking resources and script loading
Audit image and video optimization strategies
Analyze network bandwidth and connection quality

Source and maintenance

Community listingRegistry 1.9.0

mcp-registry: io.github.nucliweb/webperf-snippets@1.9.0 Source repository Project website

Maintenance checked: Oct 31, 2026, 10:27 PM UTC

Packages and installation

Source-provided package data. Koskamo has not executed or live-probed this package.

webperf-snippets 1.9.0

npm

webperf-snippets package definition

{
  "version": "1.9.0",
  "transport": "stdio",
  "identifier": "webperf-snippets",
  "registryType": "npm",
  "registryBaseUrl": "https://registry.npmjs.org",
  "packageArguments": [
    {
      "type": "positional",
      "value": "mcp"
    }
  ],
  "environmentVariables": [
    {
      "name": "CRUX_API_KEY",
      "format": "string",
      "description": "Chrome UX Report API key for the field data of get_crux; the other tools work without it"
    }
  ]
}

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Connect from your client

Each snippet configures the same source-provided package; replace placeholders before use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Cursor

Merge this local stdio configuration, replace every placeholder environment value, and restart Cursor. Koskamo has not executed this package.

Cursor configuration

{
  "mcpServers": {
    "webperf-snippets-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets@1.9.0",
        "mcp"
      ],
      "env": {
        "CRUX_API_KEY": "<YOUR_CRUX_API_KEY>"
      }
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.

Cline configuration

{
  "mcpServers": {
    "webperf-snippets-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets@1.9.0",
        "mcp"
      ],
      "env": {
        "CRUX_API_KEY": "<YOUR_CRUX_API_KEY>"
      }
    }
  }
}

VS Code

Merge this local stdio configuration, replace every placeholder environment value, and restart VS Code. Koskamo has not executed this package.

VS Code configuration

{
  "servers": {
    "webperf-snippets-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets@1.9.0",
        "mcp"
      ],
      "env": {
        "CRUX_API_KEY": "<YOUR_CRUX_API_KEY>"
      }
    }
  }
}

Claude Desktop

Merge this local stdio configuration, replace every placeholder environment value, and restart Claude Desktop. Koskamo has not executed this package.

Claude Desktop configuration

{
  "mcpServers": {
    "webperf-snippets-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "webperf-snippets@1.9.0",
        "mcp"
      ],
      "env": {
        "CRUX_API_KEY": "<YOUR_CRUX_API_KEY>"
      }
    }
  }
}

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