Core Web Vitals MCP Server

skill_read

Read a Core Web Vitals optimization playbook by name, such as LCP optimization, INP debugging, or CLS remediation, to guide performance fixes.

Instructions

Read a specialized Core Web Vitals optimization playbook (e.g. 'lcp-optimization', 'inp-debugging', 'cls-remediation').

Args: name: Name of the skill to read. Call skills_list to view available playbooks.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "name": "<name>"
    },
    "name": "skill_read"
  }
}

Input Schema

Name	Required	Description	Default
`name`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 17, 2026

TDQS

A3.9/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full behavioral burden. 'Read' and 'playbook' imply a non-destructive lookup, and the examples hint at content type, but there is no statement about what happens on an invalid name, whether content is static/cached, or any permission requirements.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose and examples are front-loaded in one sentence, and the argument note is brief. The 'Args:' block largely restates the schema parameter name, which is minor boilerplate rather than genuine waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a single-parameter read tool with an output schema already covering the return payload, the description supplies the essentials: what is read, examples of valid inputs, and where to discover names. Only the invalid-input behavior is unaddressed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0% for the single 'name' parameter, so the description must compensate. It does add value by supplying three concrete valid example values and pointing to skills_list for the full set, but it gives no format rules (casing, hyphenation, prefixing).

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Read) and resource (Core Web Vitals optimization playbook) and grounds it with concrete playbook identifiers ('lcp-optimization', 'inp-debugging', 'cls-remediation'). It is clearly distinguished from siblings like get_crux_metrics and audit_pagespeed, which gather data rather than return written guidance.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly routes the agent to skills_list to discover valid names, which is the key prerequisite for invocation. However, it never states the trigger condition (e.g., 'use before attempting CWV optimization' or 'when audit_pagespeed reports a failing metric'), leaving when-to-use implicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server