MCP Server to Relational Database

The connection generator wires a TypeScript MCP Server to a Relational Database project, making a Prisma client available to all tools registered inside createServer.

Prerequisites

Before using this generator, ensure you have:

1. A ts#mcp-server project
2. A ts#rdb project

Usage

Run the Generator

VSCode

1. Install the Nx Console VSCode Plugin if you haven't already
2. Open the Nx Console in VSCode
3. Click Generate (UI) in the "Common Nx Commands" section
4. Search for @aws/nx-plugin - connection
5. Fill in the required parameters
6. Click Generate

CLI

pnpm

pnpm nx g @aws/nx-plugin:connection

yarn

yarn nx g @aws/nx-plugin:connection

npm

npx nx g @aws/nx-plugin:connection

bun

bunx nx g @aws/nx-plugin:connection

You can also perform a dry-run to see what files would be changed

pnpm

pnpm nx g @aws/nx-plugin:connection --dry-run

yarn

yarn nx g @aws/nx-plugin:connection --dry-run

npm

npx nx g @aws/nx-plugin:connection --dry-run

bun

bunx nx g @aws/nx-plugin:connection --dry-run

Select your MCP server project as the source and your relational database project as the target. If the project contains multiple MCP server components, specify sourceComponent to disambiguate.

Options

Parameter	Type	Default	Description
sourceProject Required	string	-	The source project
targetProject Required	string	-	The target project to connect to
sourceComponent	string	-	The source component to connect from (component name, path relative to source project root, or generator id). Use '.' to explicitly select the project as the source.
targetComponent	string	-	The target component to connect to (component name, path relative to target project root, or generator id). Use '.' to explicitly select the project as the target.

Generator Output

The generator modifies server.ts in your MCP server’s source directory:

• Directorypackages/my-service/src/my-mcp

  • server.ts Prisma client fetched and available to all tools registered inside createServer

Additionally, the <mcp-server-name>-serve-local target is updated to depend on the database’s serve-local target.

How It Works

The Prisma client is fetched inside createServer and available to all tools and resources registered there:

packages/my-service/src/my-mcp/server.ts

import { getPrisma as getMyDb } from ':my-scope/my-db';

export const createServer = async () => {
  const myDb = await getMyDb();
  const server = new McpServer({ name: 'my-service', version: '1.0.0' });
  // register tools/resources that use myDb
  return server;
};

Multiple Databases

Running the generator again with a different target adds the second database alongside the first. Both are fetched inside createServer:

packages/my-service/src/my-mcp/server.ts

export const createServer = async () => {
  const postgresDb = await getPostgresDb();
  const mysqlDb = await getMysqlDb();
  const server = new McpServer({ ... });
  // register tools using both clients
  return server;
};

Infrastructure

The generated MCP server construct implements IGrantable and IConnectable, so you can grant network and IAM access to the database directly on the construct.

CDK

packages/infra/src/stacks/application-stack.ts

import { MyDatabase } from ':my-scope/common-constructs';

const db = new MyDatabase(this, 'Db', { vpc, ... });
const myMcpServer = new MyMcpServer(this, 'MyMcpServer', { vpc, ... });

db.allowDefaultPortFrom(myMcpServer);
db.grantConnect(myMcpServer);

allowDefaultPortFrom opens the security group rule so the MCP server runtime can reach the database port. grantConnect grants IAM rds-db:connect permission to the server’s execution role.

Terraform

Pass the database module outputs into your MCP server module so it can reach the database and read its runtime configuration:

packages/infra/src/main.tf

module "my_database" {
  source              = "../../common/terraform/src/app/dbs/my-database"
  vpc_id              = module.vpc.vpc_id
  database_subnet_ids = module.vpc.private_isolated_subnet_ids
}

module "my_mcp_server" {
  source = "../../common/terraform/src/app/mcp-servers/my-mcp-server"

  appconfig_application_id     = module.my_database.appconfig_application_id
  database_cluster_resource_id = module.my_database.cluster_resource_id
  database_runtime_user        = module.my_database.database_runtime_user
  database_security_group_id   = module.my_database.security_group_id
  database_port                = module.my_database.cluster_port
}

Ensure the MCP server’s execution role has rds-db:connect permission and that its security group can reach the database security group on the database port.

Local Development

pnpm

pnpm nx <mcp-server-name>-serve-local <project-name>

yarn

yarn nx <mcp-server-name>-serve-local <project-name>

npm

npx nx <mcp-server-name>-serve-local <project-name>

bun

bunx nx <mcp-server-name>-serve-local <project-name>

This starts the MCP server and all connected databases. The SERVE_LOCAL=true environment variable causes each Prisma client to connect to its local Docker database instead of Aurora.