Examples

A real-world Express + OpenAI tool-calling example, plus the smallest possible end-to-end run with no framework on either side.

Express + OpenAI (real-world example)

Two standalone, runnable projects in examples/ — an Express REST API that exposes an RCP manifest, and an AI application that discovers it and calls tools through an OpenAI tool-calling loop. Both install rcp-sdk from the real npm package, not this repo’s own source.

shell

git clone https://github.com/hasanraiyan/rcp.git && cd rcp/examples

cd express && npm install && npm start &        # your REST API + one /rcp/manifest route
cd ../openai-client && npm install               # the AI application side
cp .env.example .env                             # add your OPENAI_API_KEY
npm start -- "List my tasks, then mark the first incomplete one as done."

The two are deliberately split — examples/express has no OpenAI code, and examples/openai-client has no Express code. See examples/express and examples/openai-client on GitHub for the full source and README.

Minimal example (no framework)

The smallest possible end-to-end run — a plain Node http server exposing one tool, and a client discovering + calling it. No Express, no OpenAI, no framework on either side.

The server

One route for the manifest, one route for the tool itself. Auth is header, so the manifest fetch requires a bearer token too.

server.ts

import { createServer, type Server } from 'node:http';
import { z } from 'zod';
import { defineTool } from 'rcp-sdk/server';

const MANIFEST_TOKEN = 'demo-secret';

export const getWeather = defineTool({
  name: 'get_weather',
  description: 'Get current weather information for a city.',
  method: 'GET',
  args: z.object({
    city: z.string().describe('City name, e.g. "Paris"'),
  }),
  url: 'http://localhost:4310/weather',
  queryParams: { city: (t) => t.arg('city') },
  responseMappings: {
    temperatureC: '@temperatureC',
    conditions: '@conditions',
  },
});

const manifest = {
  rcpVersion: '0.1',
  auth: { type: 'header', header: 'Authorization', scheme: 'Bearer' },
  tools: [getWeather],
};

export function startExampleServer(port = 4310): Server {
  return createServer((req, res) => {
    if (req.url === '/manifest') {
      if (req.headers.authorization !== `Bearer ${MANIFEST_TOKEN}`) {
        res.writeHead(401).end();
        return;
      }
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(manifest));
      return;
    }

    if (req.url?.startsWith('/weather')) {
      const city = new URL(req.url, 'http://localhost').searchParams.get('city') ?? 'unknown';
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ city, temperatureC: 18, conditions: 'Partly cloudy' }));
      return;
    }

    res.writeHead(404).end();
  }).listen(port);
}

export { MANIFEST_TOKEN };

The client

run.ts

import { createRcpClient } from 'rcp-sdk/client';
import { MANIFEST_TOKEN, startExampleServer } from './server.js';

async function main() {
  const server = startExampleServer(4310);

  try {
    const client = createRcpClient({
      auth: { type: 'header', secret: MANIFEST_TOKEN },
    });

    const { manifest, tools } = await client.discover('http://localhost:4310/manifest');
    console.log(`Discovered ${tools.length} tool(s) from manifest v${manifest.rcpVersion}:`);
    for (const tool of tools) {
      console.log(`  - ${tool.name}: ${tool.description}`);
    }

    const weather = tools.find((t) => t.name === 'get_weather');
    if (!weather) throw new Error('get_weather tool not found in manifest');

    const result = await client.call(weather, { city: 'Paris' });
    console.log('\nCalled get_weather({ city: "Paris" }):');
    console.log(JSON.stringify(result.mapped, null, 2));
  } finally {
    server.close();
  }
}

main().catch((err) => {
  console.error(err);
  process.exitCode = 1;
});

Output

$ pnpm example

Discovered 1 tool(s) from manifest v0.1:
  - get_weather: Get current weather information for a city.

Called get_weather({ city: "Paris" }):
{
  "temperatureC": 18,
  "conditions": "Partly cloudy"
}

This is examples/basic in the repo, runnable as-is with pnpm example. View it on GitHub.

Gemini — rcp-sdk/adapters/gemini

RCP vs MCP