import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
import { z } from "zod/v3";
import { connectDatabaseInputSchema, DatabaseConnections } from "./connection";
import { sql } from "kysely";
const mcpServer = new McpServer({
name: "mcp-universal-db-client",
version: "0.0.0",
});
const databaseConnections = new DatabaseConnections();
mcpServer.registerTool(
"connect_database",
{
title: "Connect Database",
description: "Connect to a database using connection string",
inputSchema: connectDatabaseInputSchema.shape,
},
async (input) => {
const id = databaseConnections.addConnection(input);
return {
content: [
{
type: "text",
text: `Connected to ${input.dialect} database.`,
},
{
type: "text",
text: `Connection ID: ${id} (use this ID for future queries)`,
},
],
};
}
);
mcpServer.registerTool(
"list_connections",
{
title: "List Connections",
description: "List all active database connections",
},
async () => {
const connections = databaseConnections.getAllConnections();
return {
content: [
{
type: "text",
text: JSON.stringify({
connections: connections,
}),
},
],
};
}
);
mcpServer.registerTool(
"disconnect_database",
{
title: "Disconnect Database",
description: "Disconnect from a database using connection ID",
inputSchema: {
connectionID: z.string().describe("The connection ID to disconnect"),
},
},
async (input) => {
databaseConnections.deleteConnection(input.connectionID);
return {
content: [
{
type: "text",
text: `Disconnected connection ID: ${input.connectionID}`,
},
],
};
}
);
mcpServer.registerTool(
"disconnect_all",
{
title: "Disconnect All",
description: "Disconnect all active database connections",
},
async () => {
await databaseConnections.deleteAllConnections();
return {
content: [
{
type: "text",
text: "All connections have been disconnected.",
},
],
};
}
);
mcpServer.registerTool(
"run_query",
{
title: "Run SQL Query",
description: "Run SQL query on the connected database",
inputSchema: {
connectionID: z.string().describe("The connection ID"),
query: z.string().array().describe("The SQL queries to execute"),
},
},
async (input) => {
const connection = databaseConnections.getConnection(input.connectionID);
if (!connection) {
return {
content: [
{
type: "text",
text: `No active connection found for ID: ${input.connectionID}`,
},
],
};
}
let results = [];
for (const query of input.query) {
const q = sql.raw(query).compile(connection.instance);
const result = await connection.instance.executeQuery(q);
results.push({ query, res: result });
}
return {
content: [
{
type: "text",
text: JSON.stringify({ results }),
},
],
};
}
);
const main = async () => {
const transport = new StdioServerTransport();
await mcpServer.connect(transport);
};
main().catch((err) => {
console.error(err);
process.exit(1);
});
