multi-db-mcp

An MCP server for read-only SQL against several named databases (local, staging, production, …) from one place. It supports MySQL (including MariaDB and Aurora) and Postgres.

Safety model

Even so, give each entry a database user that only has read access. These checks protect you, but they shouldn't replace proper grants.

Related MCP server: Common Database MCP Server

Setup

npm install
npm run build
cp databases.example.json databases.json   # edit it
cp .env.example .env                       # put passwords here

Any string in databases.json can use ${ENV_VAR}. Variables come from the MCP client's env or from a .env file next to the config. Variables already set in the environment take priority. If an entry is broken (for example, a variable is missing), that entry is skipped and reported by list_databases; the other entries still work.

Config reference

{
  "defaults": { "maxRows": 200, "timeoutMs": 15000 },
  "databases": {
    "<name>": {
      "engine": "mysql" | "postgres",
      "host": "...", "port": 3306, "user": "...", "password": "${VAR}", "database": "...",
      "description": "shown to the model",
      "ssl": true | { "rejectUnauthorized": true, "caFile": "certs/rds-global-bundle.pem" },
      "requireReplica": true,      // force the replica check on a localhost tunnel
      "maxRows": 200, "timeoutMs": 15000
    }
  }
}

The config is read from the MULTI_DB_CONFIG env var, then from the first CLI argument, then from databases.json in the project root.

Register with Claude Code

claude mcp add multi-db --scope user -- node D:/Projects/multi-db-mcp/dist/index.js

To use a config stored somewhere else, set the env var: claude mcp add multi-db --scope user -e MULTI_DB_CONFIG=C:/path/databases.json -- node D:/Projects/multi-db-mcp/dist/index.js.

Tools

• list_databases: lists the configured entries. Pass checkConnections: true to also get each one's version and replica status.

• query: runs one read statement against a named database, with optional positional params and maxRows.

• list_tables: lists tables and views with approximate row counts.

• describe_table: shows a table's columns and indexes.

Development

npm test          # safety unit tests
npm run dev       # run from source with tsx