DBConvert Streams — MCP server

Read-only SQL across your PostgreSQL, MySQL, S3-compatible buckets and folders of Parquet, CSV and JSON files — and one query can join across all of them, federated in-process by DuckDB.

npx @dbconvert/stream-mcp "shop=postgres://user:password@host:5432/shop"

Several sources at once, each optionally named:

npx @dbconvert/stream-mcp \
  shop=postgres://user:password@host:5432/shop \
  orders=mysql://user:password@host:3306/orders \
  lake=s3://analytics/exports?region=eu-central-1 \
  /home/you/data

Ask which customers sit in the PostgreSQL database but are missing from the MySQL one, or whether the CSV someone sent last week still matches the live table — it answers with a single query. No copying, no staging table, no pipeline.

In a client's configuration

{
  "mcpServers": {
    "dbconvert": {
      "command": "npx",
      "args": ["-y", "@dbconvert/stream-mcp",
               "shop=postgres://user:password@host:5432/shop",
               "orders=mysql://user:password@host:3306/orders",
               "/home/you/data"]
    }
  }
}

Sources can also arrive in one DBCONVERT_MCP_SOURCES environment variable, separated by spaces — that is what VS Code's install prompt fills in, and what docker run -e takes. Arguments win if you use both.

It cannot write

There is no tool here that updates a row, drops a table or alters a schema — absent, not disabled. Every tool declares readOnlyHint, so a client can check rather than trust. Connection details are given once, at startup, and never travel through a tool call into the conversation or the logs.

What this package contains

Kilobytes. The server itself is a native binary with DuckDB linked in, so it is downloaded from the GitHub release on first use, checked against a SHA-256 that ships inside this package, and cached under ~/.cache/dbconvert-streams/ (%LOCALAPPDATA% on Windows).

Which platforms

| Your machine | npx @dbconvert/stream-mcp | Docker image | | --- | --- | --- | | Linux x64 | yes | yes | | Windows x64 | yes | yes, through Docker Desktop | | macOS (Intel or Apple silicon) | not yet | yes, through Docker Desktop | | Linux or Windows on ARM | not yet | not yet |

A native macOS build is planned. Until it exists, macOS users run the same server as a container — it behaves identically, because it is the same binary built for Linux:

docker run -i --rm slotix/stream-mcp "postgres://user:password@host:5432/db"

On an unsupported platform this launcher says so and points at that command rather than failing with a download error.

S3 credentials come from AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY, never from the URL. LOG_FILE defaults to the cache directory — stdout carries the MCP protocol, so the server will not start without somewhere to log.

Documentation: https://streams.dbconvert.com/docs/mcp/standalone

The server is proprietary software, distributed under the DBConvert Streams licence; this launcher is part of the same distribution.