W3c Mcp Server

by shuji-bonji

296 downloads

Not rated

GitHub

About

MCP Server for accessing W3C/WHATWG/IETF web specifications. Provides AI assistants with access to official web standards data including specifications, WebIDL definitions, CSS properties, and HTML elements.

Details

Author: shuji-bonji
Downloads: 296
Categories: Other, Knowledge Base

- Specification discovery with filtering by organization and keyword
- WebIDL interface definitions for JavaScript APIs
- CSS property definitions by specification or name
- HTML element definitions from multiple specs
- PWA-related specification grouping and dependency info
- Fast startup (~70ms) and O(1) spec lookups

Setting up with Highlight

This MCP is not yet compatible with Highlight’s one-click setup. However, you can still use it with Highlight by following these steps:

Download and install Highlight from highlightai.com/download
Navigate to the plugins tab and select "Add Custom Plugin"
Configure the plugin with the settings below

Plugin Name W3c Mcp Server

Command (node, npx, python, etc.)

Please refer to the README for specific instructions on how to obtain API keys or other required environment variables.
Enable "Start Automatically" if you want the plugin to start when Highlight launches

Setting up with Cursor

Open Cursor's settings
Navigate to the MCP section
Click "Add new Global MCP server"
Copy and paste the configuration below based on your operating system

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

Setting up with Claude Desktop

Open Claude Desktop's settings
Go to the Integrations tab
Click "Add MCP Server"
Use the configuration below based on your operating system

Note: Make sure Claude Desktop is running before attempting to connect.

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

Setting up with Windsurf

Open Windsurf's preferences
Go to the Integrations section
Click "Add MCP Integration"
Use the configuration below based on your operating system

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

Setting up with Cline

Open Cline's settings
Navigate to the Integrations section
Click "Add MCP Server"
Copy and paste the configuration below based on your operating system

Note: Make sure to restart Cline after adding the configuration.

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

Setting up with Goose

Open Goose's preferences
Go to the Integrations tab
Select "MCP Servers"
Click "Add New Server"
Use the configuration below based on your operating system

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

JSON

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

From the repository

Install globally via npm install -g @shuji-bonji/w3c-mcp or use directly with npx @shuji-bonji/w3c-mcp. Configure it in Claude Desktop or Cursor by adding a JSON entry with the npx command. Enable debug logging with W3C_MCP_DEBUG=true or W3C_MCP_PERF=true environment variables.

`list_w3c_specs`

List W3C/WHATWG/IETF web specifications with optional filtering by organization, keyword, or category

`get_w3c_spec`

Get detailed information about a specific web specification including URLs, status, repository, and test info

`search_w3c_specs`

Search web specifications by query string, searching in title, shortname, and description

`get_webidl`

Get WebIDL interface definitions for a specification. WebIDL defines the JavaScript APIs.

`list_webidl_specs`

List all specifications that have WebIDL definitions available

`get_css_properties`

Get CSS property definitions from a specific spec or all specs

`list_css_specs`

List all CSS specifications that have property definitions available

`get_html_elements`

Get HTML element definitions from a specific spec or all specs

`list_element_specs`

List all specifications that have HTML element definitions available

`get_pwa_specs`

Get all Progressive Web App (PWA) related specifications including Service Worker, Web App Manifest, Push API, Background Sync, etc.

`get_spec_dependencies`

[DEPRECATED] Returns only basic spec metadata with empty dependencies/dependents arrays (upstream web-specs does not expose dependency data). Scheduled for removal in the next major release — use get_w3c_spec instead.

Claude Desktop / Cursor

Paste into your MCP client config file to install this server.

{
    "mcpServers": {
        "w3c mcp server": {
            "w3c": {
                "command": "npx",
                "args": [
                    "-y",
                    "@shuji-bonji/w3c-mcp"
                ]
            }
        }
    }
}

McpServers

{
    "w3c": {
        "command": "npx",
        "args": [
            "-y",
            "@shuji-bonji/w3c-mcp"
        ]
    }
}

W3C MCP Server

Installation

bash
npm install -g @shuji-bonji/w3c-mcp



Or use directly with npx:

bash
npx @shuji-bonji/w3c-mcp



Configuration


Claude Desktop


Add to your Claude Desktop configuration file:

macOS:

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


Windows:

%APPDATA%\Claude\claude_desktop_config.json

json
{
  "mcpServers": {
    "w3c": {
      "command": "npx",
      "args": ["-y", "@shuji-bonji/w3c-mcp"]
    }
  }
}



Cursor


Add to your Cursor MCP settings (

.cursor/mcp.json

 in your project or global settings):

json
{
  "mcpServers": {
    "w3c": {
      "command": "npx",
      "args": ["-y", "@shuji-bonji/w3c-mcp"]
    }
  }
}



Available Tools


Specification Discovery

list_w3c_specs


List W3C/WHATWG/IETF web specifications with optional filtering.

Parameters:
-

organization (optional): Filter by organization - "W3C", "WHATWG", "IETF", or "all"

keyword

 (optional): Filter by keyword in title or shortname
-

get_w3c_spec


Get detailed information about a specific web specification.

Parameters:
-

shortname (required): Specification shortname (e.g., "service-workers", "appmanifest", "fetch"

search_w3c_specs


Search web specifications by query string.

Parameters:
-

query (required): Search query (e.g., "service worker", "manifest", "storage"

)
-

limit

 (optional): Maximum number of results (default: 20)

WebIDL

get_webidl


Get WebIDL interface definitions for a specification. WebIDL defines the JavaScript APIs.

Parameters:
-

shortname (required): Specification shortname (e.g., "service-workers", "fetch", "dom"

list_webidl_specs


List all specifications that have WebIDL definitions available.

CSS

get_css_properties


Get CSS property definitions from a specific spec or all specs.

Parameters:
-

spec (optional): Specification shortname (e.g., "css-grid-1", "css-flexbox-1"

)
-

property

 (optional): Search for a specific CSS property by name

list_css_specs


List all CSS specifications that have property definitions available.

HTML Elements

get_html_elements


Get HTML element definitions from a specific spec or all specs.

Parameters:
-

spec (optional): Specification shortname (e.g., "html", "svg"

)
-

element (optional): Search for a specific element by name (e.g., "video", "canvas"

list_element_specs


List all specifications that have HTML element definitions available.

PWA

get_pwa_specs


Get all Progressive Web App (PWA) related specifications.

Parameters:
-

coreOnly

 (optional): If true, return only the core PWA specs (Service Worker, Manifest, Push, Notifications)

get_spec_dependencies


Get dependency information for a specification.

Parameters:
-

shortname

 (required): Specification shortname

Usage Examples


Find Service Worker APIs


Use the get_webidl tool with shortname "service-workers" to see the ServiceWorker interface definitions.



Explore PWA Technologies


Use get_pwa_specs to see all PWA-related specifications, then use get_w3c_spec for details on each one.



Look up CSS Grid Properties


Use get_css_properties with spec "css-grid-1" to see all CSS Grid layout properties.



Search for Storage APIs


Use search_w3c_specs with query "storage" to find all storage-related specifications.



Data Sources


This MCP server uses the following W3C/webref data packages:

| Package | Description |
|---------|-------------|
| web-specs | Metadata for all web specifications |
| @webref/idl | WebIDL interface definitions |
| @webref/css | CSS properties and values |
| @webref/elements | HTML element definitions |

These packages are maintained by the W3C and provide machine-readable data extracted from official specifications.

GitHub Repositories:
- https://github.com/w3c/browser-specs
- https://github.com/w3c/webref

Debug Mode


Enable debug logging with environment variables:

``bash

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About

Details

Jump to

Setting up with Highlight

From the repository

list_w3c_specs

get_w3c_spec

search_w3c_specs

get_webidl

list_webidl_specs

get_css_properties

list_css_specs

get_html_elements

list_element_specs

get_pwa_specs

get_spec_dependencies

Claude Desktop / Cursor

McpServers

W3C MCP Server

Installation

Configuration

Claude Desktop

Cursor

Available Tools

Specification Discovery

list_w3c_specs

get_w3c_spec

search_w3c_specs

WebIDL

get_webidl

list_webidl_specs

CSS

get_css_properties

list_css_specs

HTML Elements

get_html_elements

list_element_specs

PWA

get_pwa_specs

get_spec_dependencies

Usage Examples

Find Service Worker APIs

Explore PWA Technologies

Look up CSS Grid Properties

Search for Storage APIs

Data Sources

Debug Mode

Install

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`list_w3c_specs`

`get_w3c_spec`

`search_w3c_specs`

`get_webidl`

`list_webidl_specs`

`get_css_properties`

`list_css_specs`

`get_html_elements`

`list_element_specs`

`get_pwa_specs`

`get_spec_dependencies`