DB Explorer MCP server

DB Explorer MCP

A read-only Model Context Protocol (MCP) server for PostgreSQL, MySQL, and SQLite that lets an AI coding assistant explore, query, and audit a relational database without ever being able to write to it.

<!-- mcp-name: io.github.AYUSH-148/db-explorer-mcp-server -->

Point your MCP client at a database and ask questions in plain language. The client's LLM writes the SQL; this server parses it, refuses anything that is not a single read-only SELECT, executes it with a row cap, and returns structured results. Schema inspection, execution plans, index recommendations, and migration review come along with it.

MCP client LLM  ->  FastMCP tools  ->  safety layer  ->  SQLAlchemy  ->  database
   (writes SQL)       (7 tools)       (rejects writes)   (any dialect)

The server makes no LLM API calls of its own, so there is no API key to configure — reasoning happens in whichever client you connect. Works with SQLite, PostgreSQL, and MySQL through SQLAlchemy.

Tested and evaluated. 336 tests run on every push and pull request, plus 26 more against real PostgreSQL and MySQL in CI (Tests). In an agent evaluation, Claude completed 14 of 14 realistic database tasks through these tools with no failed tool calls, an average of 2 calls per task, and a mean independent judge score of 4.6 / 5 (Agent evals).

Why

Giving an assistant raw database credentials means one confused or prompt-injected turn can drop a table. Handing it a read-only replica loses schema context and plan analysis. This server takes the middle path: full introspection and query power, with mutation made structurally impossible at the parser level rather than by asking the model to behave.

Architecture

┌──────────────────────────────────────────────────────────────┐
│  MCP client  (Claude Code / Claude Desktop / Inspector)      │
│  owns the LLM: reads schema, authors SQL, interprets results │
└───────────────────────────┬──────────────────────────────────┘
                            │  MCP  ·  stdio (local)
                            │        ·  streamable HTTP + bearer token (remote)
┌───────────────────────────▼──────────────────────────────────┐
│ server.py  —  FastMCP instance + one engine per token group  │
│                                                              │
│   explore_schema   execute_query    explain_query            │
│   validate_schema  suggest_index    migration_context        │
│   validate_migration                                         │
└──────┬───────────────────────┬───────────────────┬───────────┘
       │                       │                   │
       │  read path            │  metadata path    │  review path
       │                       │                   │
┌──────▼────────────┐  ┌───────▼─────────┐  ┌──────▼──────────┐
│ safety.py         │  │ inspector.py    │  │ migration.py    │
│ ── trust boundary │  │ schema_health.py│  │ parses

Shortened. The full README is on GitHub.