index.ts•8.96 kB
#!/usr/bin/env node
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import express from 'express';
import { randomUUID } from 'node:crypto';
import { z } from 'zod';
import {
TextContent,
isInitializeRequest,
} from '@modelcontextprotocol/sdk/types.js';
import dotenv from 'dotenv';
import config from './config/index.js';
import { PerplexityService } from './services/perplexity.js';
// Load environment variables
dotenv.config();
class McpServerApp {
private perplexityService: PerplexityService;
private systemPrompt = {
role: 'system',
content: `You are a helpful AI assistant.
Rules:
1. Provide only the final answer. It is important that you do not include any explanation on the steps below.
2. Do not show the intermediate steps information.
Steps:
1. Decide if the answer should be a brief sentence or a list of suggestions.
2. If it is a list of suggestions, first, write a short brief and natural introduction based on the original query.
3. Followed by a list of suggestions, each suggestion should be split by two newlines.`,
};
constructor() {
this.perplexityService = new PerplexityService();
}
private createServer(): McpServer {
const server = new McpServer({
name: 'mcp-perplexity-server',
version: '1.0.0',
});
// Register Perplexity Ask tool
server.tool(
'perplexity_ask',
'Engages in a conversation using the Sonar API. Accepts an array of messages (each with a role and content) and returns a chat completion response from the Perplexity model.',
{
messages: z
.array(
z.object({
role: z
.string()
.describe(
'Role of the message (e.g., system, user, assistant)'
),
content: z.string().describe('The content of the message'),
})
)
.describe('Array of conversation messages'),
},
async ({ messages }) => {
try {
const result = await this.perplexityService.ask([
this.systemPrompt,
...messages,
]);
return {
content: [
{
type: 'text',
text: result,
} as TextContent,
],
};
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : String(error);
throw new Error(`Error executing perplexity_ask: ${errorMessage}`);
}
}
);
// Register Perplexity Research tool
server.tool(
'perplexity_research',
'Performs deep research using the Perplexity API. Accepts an array of messages (each with a role and content) and returns a comprehensive research response with citations.',
{
messages: z
.array(
z.object({
role: z
.string()
.describe(
'Role of the message (e.g., system, user, assistant)'
),
content: z.string().describe('The content of the message'),
})
)
.describe('Array of conversation messages'),
},
async ({ messages }) => {
try {
const result = await this.perplexityService.research([
this.systemPrompt,
...messages,
]);
return {
content: [
{
type: 'text',
text: result,
} as TextContent,
],
};
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : String(error);
throw new Error(
`Error executing perplexity_research: ${errorMessage}`
);
}
}
);
// Register Perplexity Reason tool
server.tool(
'perplexity_reason',
'Performs reasoning tasks using the Perplexity API. Accepts an array of messages (each with a role and content) and returns a well-reasoned response using the sonar-reasoning-pro model.',
{
messages: z
.array(
z.object({
role: z
.string()
.describe(
'Role of the message (e.g., system, user, assistant)'
),
content: z.string().describe('The content of the message'),
})
)
.describe('Array of conversation messages'),
},
async ({ messages }) => {
try {
const result = await this.perplexityService.reason([
this.systemPrompt,
...messages,
]);
return {
content: [
{
type: 'text',
text: result,
} as TextContent,
],
};
} catch (error) {
const errorMessage =
error instanceof Error ? error.message : String(error);
throw new Error(`Error executing perplexity_reason: ${errorMessage}`);
}
}
);
return server;
}
async run() {
const app = express();
app.use(express.json());
// Map to store transports by session ID for stateful connections
const transports: { [sessionId: string]: StreamableHTTPServerTransport } =
{};
// Health check endpoint
app.get('/health', (req, res) => {
res.json({ status: 'ok', service: 'mcp-perplexity-server' });
});
// Handle POST requests for client-to-server communication
app.post('/mcp', async (req, res) => {
try {
// Check for existing session ID
const sessionId = req.headers['mcp-session-id'] as string | undefined;
let transport: StreamableHTTPServerTransport;
let server: McpServer;
if (sessionId && transports[sessionId]) {
// Reuse existing transport
transport = transports[sessionId];
} else if (!sessionId && isInitializeRequest(req.body)) {
// New initialization request
transport = new StreamableHTTPServerTransport({
sessionIdGenerator: () => randomUUID(),
onsessioninitialized: sessionId => {
// Store the transport by session ID
transports[sessionId] = transport;
},
});
// Clean up transport when closed
transport.onclose = () => {
if (transport.sessionId) {
delete transports[transport.sessionId];
}
};
// Create new server instance
server = this.createServer();
// Connect to the MCP server
await server.connect(transport);
} else {
// Invalid request
res.status(400).json({
jsonrpc: '2.0',
error: {
code: -32000,
message: 'Bad Request: No valid session ID provided',
},
id: null,
});
return;
}
// Handle the request
await transport.handleRequest(req, res, req.body);
} catch (error) {
console.error('Error handling MCP request:', error);
if (!res.headersSent) {
res.status(500).json({
jsonrpc: '2.0',
error: {
code: -32603,
message: 'Internal server error',
},
id: null,
});
}
}
});
// Reusable handler for GET and DELETE requests
const handleSessionRequest = async (
req: express.Request,
res: express.Response
) => {
const sessionId = req.headers['mcp-session-id'] as string | undefined;
if (!sessionId || !transports[sessionId]) {
res.status(400).send('Invalid or missing session ID');
return;
}
const transport = transports[sessionId];
await transport.handleRequest(req, res);
};
// Handle GET requests for server-to-client notifications via SSE
app.get('/mcp', handleSessionRequest);
// Handle DELETE requests for session termination
app.delete('/mcp', handleSessionRequest);
// Start the server
app.listen(config.server.port, '0.0.0.0', () => {
console.log(
`MCP Perplexity Server running on http://0.0.0.0:${config.server.port}`
);
console.log(
`Health check available at http://0.0.0.0:${config.server.port}/health`
);
console.log(
`MCP endpoint available at http://0.0.0.0:${config.server.port}/mcp`
);
});
}
}
// Start the server
const server = new McpServerApp();
server.run().catch(error => {
console.error('Failed to start server:', error);
process.exit(1);
});
// Handle server shutdown
process.on('SIGINT', async () => {
console.log('Shutting down server...');
process.exit(0);
});