# webperf-snippets

Run curated WebPerf Snippets headlessly via Playwright. Diagnose Core Web Vitals beyond what Lighthouse exposes.

- **Type:** MCP server
- **Trust:** 85/100 (A), scored on the package rubric
- **Verification:** verified (build provenance)
- **Version:** 1.1.0
- **Author:** Joan Leon | @nucliweb
- **License:** MIT
- **npm:** webperf-snippets
- **Source:** https://github.com/nucliweb/webperf-snippets
- **Compatible clients:** claude-code, cursor, copilot, gemini (basis: transport)

## Trust

85/100 (A), scored on the package rubric
- Publisher verified: no
- Build provenance: verified attestation
- npm trusted publishing (OIDC): yes
- Install scripts: nothing suspicious found
- Prompt-injection scan: not run
- Obfuscation scan: not run
- Evidence age: 0 days

## Security scan

- **Status:** clean
- **Scanned:** 2026-10-22T13:44:27.101Z
- **Version scanned:** 1.2.0
- **CVEs:** none found by OSV at scan time

## Tools

8 declared. Statically extracted from the shipped source — a floor on the surface, not a census.
- `list_snippets` — Lists the web performance snippets this server can run, with their category, title and short aliases. Call it to find the name of the snippet to run.
- `run_snippet` — Opens the URL in a headless Chromium, runs one web performance snippet on the loaded page and returns the object the snippet returns, as defined in snippets/SCH
- `run_workflow` — Opens the URL in a headless Chromium and runs a workflow: a sequence of snippets plus the follow-ups its decision tree adds from the results (for example LCP-Su
- `get_crux` — Returns the p75 of LCP, CLS and INP that real Chrome users had on a URL over the last 28 days, from the Chrome UX Report, with their rating. Falls back to the o
- `open_page` — Opens the URL in a headless Chromium that stays open between calls, and installs the snippets that record interactions (INP, Interactions, Input-Latency-Breakdo
- `interact` — Runs steps on a page opened with open_page, as a person would: click, type, hover, scroll or wait. A click or a key press is what the tracking snippets record. 
- `read_results` — Returns what the tracking snippets installed by open_page have recorded on the page so far, as the objects they return. A snippet with nothing recorded yet answ
- `close_page` — Closes a page opened with open_page. Closing a page that is already closed is not an error.

## Install

**Verdict: install** — No blocking findings and no open coverage gaps — safe to install as configured.
**Config** (claude-code):
```json
"{\n  \"mcpServers\": {\n    \"webperf-snippets\": {\n      \"command\": \"npx\",\n      \"args\": [\n        \"-y\",\n        \"webperf-snippets\"\n      ],\n      \"env\": {\n        \"CRUX_API_KEY\": \"<YOUR_CRUX_API_KEY>\"\n      }\n    }\n  }\n}"
```
**Credentials it will ask for** (names only — Forge never holds a value):
- `CRUX_API_KEY` — Crux API Key (optional)
Placeholders only. Forge never holds, brokers, or transmits a credential value — replace each <YOUR_NAME> in your own config file. Do not send a value back to Forge; no Forge endpoint accepts one.
- This entry needs 1 credential (0 required). The generated config carries placeholders, so it will fail in the editor rather than at runtime if they are left unset.

## Blast radius

Moderate blast radius — holds an api key; runs on your machine.
- Floor 22, ceiling 22 (tier: moderate)
- This is impact, not likelihood. A high radius is not a defect: a filesystem server is supposed to write files. It is never part of the trust score.

## Machine-readable views of this entry

- Signed JSON: https://forgeregistry.com/api/v1/packages/webperf-snippets
- Install plan: https://forgeregistry.com/api/v1/packages/webperf-snippets/install-plan
- Alternatives: https://forgeregistry.com/api/v1/alternatives/webperf-snippets
- HTML page: https://forgeregistry.com/registry/webperf-snippets
- MCP: POST https://forgeregistry.com/api/mcp → `forge_get_package` / `forge_install_plan`

## About this document

Generated by Forge (https://forgeregistry.com) — a compact rendering of the same record served, signed, at the JSON URL above. Trust and scan facts are the registry's own measurements; anything Forge did not measure is named as unmeasured rather than omitted.