H3
Minimal MCP server built with H3 v2 (beta) as a dedicated app or nested-app.
What is H3?
H3 is a Model Context Protocol (MCP) server that allows AI assistants like Claude, Cursor, and VS Code to minimal mcp server built with h3 v2 (beta) as a dedicated app or nested-app.
Minimal MCP server built with H3 v2 (beta) as a dedicated app or nested-app.
This server falls under the Developer Tools category on MCPgee, the world's largest MCP server directory with 33,000+ servers.
Features
- Minimal MCP server built with H3 v2 (beta) as a dedicated ap
Use Cases
Maintainer
Works with
Installation
Manual Installation
npx h3-mcp-toolsConfiguration
Configuration Details
claude_desktop_config.json
Performance
Response Metrics
Resource Usage
How to Set Up and Use H3
H3 MCP Tools is a TypeScript library built on the H3 v2 (beta) web framework that lets developers create lightweight, embeddable MCP servers with minimal boilerplate—either as standalone apps or as nested sub-apps within an existing H3 server—using standard JSON-RPC over HTTP or stdio transports.
Prerequisites
- Node.js 18 or higher
- A package manager: npm, yarn, pnpm, bun, or deno
- Basic TypeScript/JavaScript knowledge
- An existing H3 v2 project or willingness to create one
- Claude Desktop or another MCP-compatible client for testing
Install h3-mcp-tools in your project
Add the h3-mcp-tools package to your project. The package uses nypm for auto-detecting your package manager.
# npm
npm install h3-mcp-tools
# pnpm
pnpm add h3-mcp-tools
# bun
bun add h3-mcp-tools
# Or using nypm (auto-detects package manager)
npx nypm install h3-mcp-toolsCreate a basic MCP server with H3
Import H3MCP from h3-mcp-tools, create an H3 app, and register your first tool using the app.tool() method.
import { createApp } from 'h3'
import { H3MCP } from 'h3-mcp-tools'
import * as v from 'valibot'
const app = createApp()
const mcp = new H3MCP({
name: 'my-mcp-server',
version: '1.0.0',
description: 'My custom MCP server built with H3'
})
mcp.tool(
{
name: 'echo',
description: 'Echoes back the provided input',
schema: v.object({ input: v.string() })
},
async ({ input }) => ({ output: `You said: ${input}` })
)
mcp.register(app)Register a resource
Use app.resource() to expose static or dynamic data that AI clients can read.
mcp.resource(
{ name: 'config', uri: 'config://settings' },
async () => ({
contents: [{ uri: 'config://settings', text: JSON.stringify({ version: '1.0' }) }]
})
)Start the H3 server
Start the server using Nitro's toNodeListener or your preferred H3 adapter. The MCP endpoint is available at POST /mcp.
import { toNodeListener } from 'h3'
import { createServer } from 'node:http'
const server = createServer(toNodeListener(app))
server.listen(3000, () => {
console.log('MCP server running at http://localhost:3000/mcp')
})Configure Claude Desktop to connect via HTTP
Add your running H3 MCP server to the Claude Desktop configuration using the HTTP transport.
{
"mcpServers": {
"h3-mcp": {
"command": "node",
"args": ["/absolute/path/to/your/server.js"]
}
}
}H3 Examples
Client configuration
Claude Desktop config running an H3 MCP server script directly via Node.js.
{
"mcpServers": {
"h3-mcp": {
"command": "node",
"args": ["/Users/yourname/my-h3-mcp/server.js"]
}
}
}JSON-RPC tool call example
Example of calling an H3 MCP tool directly via POST request to the /mcp endpoint.
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "echo",
"arguments": { "input": "hello world" }
}
}Prompts to try
Example prompts once your custom H3 MCP tools are registered and connected.
- "Call the echo tool with the message 'Hello from Claude'"
- "List all available tools on this MCP server"
- "Read the config resource from config://settings"
- "What tools does this custom MCP server expose?"
- "Use the MCP server to process this data and return the result"Troubleshooting H3
H3MCP is not a constructor or import errors after installation
H3 v2 is currently in beta and h3-mcp-tools depends on it. Ensure you have h3 v2 installed: `npm install h3@next`. Check that your tsconfig.json has moduleResolution set to 'bundler' or 'node16' to resolve ESM exports correctly.
Tools list endpoint returns empty or MCP handshake fails
Verify you called mcp.register(app) after all tool() and resource() calls. The order matters—tools registered after register() may not appear. Also confirm the POST /mcp endpoint is reachable by running `curl -X POST http://localhost:3000/mcp -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'`.
Claude Desktop cannot connect to the H3 MCP server
Claude Desktop requires the MCP server to communicate over stdio when launched as a child process. Ensure your server script handles stdio transport when invoked from the command line, or use a stdio wrapper. H3 MCP Tools supports a defineMcpHandler() for sub-app use which may be more suitable for stdio mode.
Frequently Asked Questions about H3
What is H3?
H3 is a Model Context Protocol (MCP) server that minimal mcp server built with h3 v2 (beta) as a dedicated app or nested-app. It connects AI assistants to external tools and data sources through a standardized interface.
How do I install H3?
Follow the installation instructions on the H3 GitHub repository. Clone the repo, install dependencies, and add the server config to your AI client.
Which AI clients work with H3?
H3 works with all major MCP-compatible AI clients including Claude Desktop, Claude Code, Cursor, VS Code (GitHub Copilot), Windsurf, and Cline.
Is H3 free to use?
Yes, H3 is open source and available under the MIT license. You can use it freely in both personal and commercial projects.
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Quick Config Preview
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