MCP 服务器

mysql-readonly-mcp

Provides secure, read-only access to a single MySQL database for schema inspection and querying.

README

MySQL Read-Only MCP Server

MySQL Read-Only MCP Server is a Model Context Protocol (MCP) server that provides secure, read-only access to a single MySQL database. It is designed for MCP-compatible clients that need to inspect schema details, preview table data, and run analytical queries without allowing data or schema changes.

Overview

Read-only query execution for MySQL
Single database configuration per server instance
Built-in query validation and row limits
Schema inspection and relationship discovery tools
Compatible with MCP clients such as Claude Desktop and editor integrations

Installation

Run with npx

npx -y mysql-readonly-mcp

Prefer npx or a globally installed binary in MCP client configuration. Do not point MCP clients to a cloned repository checkout such as .../mysql-readonly-mcp/dist/index.js, because some clients and agents may treat that checkout as part of the active workspace.

Global installation

npm install -g mysql-readonly-mcp
mysql-readonly-mcp

Configuration

The server reads its connection settings from environment variables.

Variable	Description	Default
`MYSQL_HOST`	MySQL host	`localhost`
`MYSQL_PORT`	MySQL port	`3306`
`MYSQL_USER`	MySQL user	`root`
`MYSQL_PASSWORD`	MySQL password	empty
`MYSQL_DATABASE`	Database name	`mysql`
`MYSQL_QUERY_TIMEOUT_MS`	Query execution timeout in milliseconds (minimum `1000`)	`30000`

Each server instance connects to one database. To work with multiple databases, configure multiple MCP server entries and point each one to a different MYSQL_DATABASE value.

Client setup

Claude Desktop

Configuration file locations:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "mysql-production": {
      "command": "npx",
      "args": ["-y", "mysql-readonly-mcp"],
      "env": {
        "MYSQL_HOST": "localhost",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "readonly_user",
        "MYSQL_PASSWORD": "your-password",
        "MYSQL_DATABASE": "production_db"
      }
    }
  }
}

Generic MCP configuration

{
  "mcpServers": {
    "mysql": {
      "command": "npx",
      "args": ["-y", "mysql-readonly-mcp"],
      "env": {
        "MYSQL_HOST": "localhost",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "root",
        "MYSQL_PASSWORD": "password",
        "MYSQL_DATABASE": "app_db"
      }
    }
  }
}

This is the recommended setup for editor and assistant clients because it keeps the MCP server isolated from the repository source tree.

Multiple database connections

Use separate MCP server entries when you need access to more than one database.

{
  "mcpServers": {
    "mysql-production": {
      "command": "npx",
      "args": ["-y", "mysql-readonly-mcp"],
      "env": {
        "MYSQL_HOST": "prod-db.example.com",
        "MYSQL_USER": "readonly_user",
        "MYSQL_PASSWORD": "your-password",
        "MYSQL_DATABASE": "production"
      }
    },
    "mysql-staging": {
      "command": "npx",
      "args": ["-y", "mysql-readonly-mcp"],
      "env": {
        "MYSQL_HOST": "staging-db.example.com",
        "MYSQL_USER": "readonly_user",
        "MYSQL_PASSWORD": "your-password",
        "MYSQL_DATABASE": "staging"
      }
    }
  }
}

Available tools

Tool	Purpose	Parameters
`list_tables`	List tables and views with metadata	None
`describe_table`	Describe table columns, keys, and indexes	`table`
`preview_data`	Preview rows from a table	`table`, `columns`, `limit`, `where`
`run_query`	Execute validated read-only SQL	`query`, `limit`
`show_relations`	Show incoming and outgoing foreign key relations	`table`
`db_stats`	Summarize database size and largest tables	None
`db_info`	Show which database this server instance is connected to	None

Tool details

`list_tables`

Returns table name, table type, row count estimate, and storage engine for the configured database.

`describe_table`

Returns:

Column definitions
Primary key columns
Foreign key relationships
Index information

`preview_data`

Parameters:

table (required)
columns (optional)
limit (optional, default 10, max 100)
where (optional basic filter expression, without the WHERE keyword)

For complex filtering, joins, unions, or advanced SQL expressions, use run_query instead of preview_data.

`run_query`

Accepted statements:

SELECT
SHOW
DESCRIBE
EXPLAIN

Rejected statements include data modification, schema modification, and permission-changing queries such as INSERT, UPDATE, DELETE, DROP, ALTER, CREATE, GRANT, REVOKE, and LOCK.

`show_relations`

Returns:

Tables that reference the target table
Tables referenced by the target table
Relationship type when it can be inferred

`db_stats`

Returns:

Total table count
Estimated total row count
Total database size
Largest tables by row count
Largest tables by size

`db_info`

Returns the connection details for this server instance: database name, host, port, user, and active query timeout. Useful when multiple MCP server instances are configured and you need to confirm which one you are addressing. The password is never included in the output.

Prompts

The server exposes a connection_info prompt for MCP clients that support prompts. When retrieved, it provides a summary of the database this server connects to and a reminder that the server is scoped to that single database. This helps LLM clients avoid routing queries to the wrong server instance.

Security model

The server is intended for inspection and analysis, not for write operations.

Query validation blocks non-read-only statements
Preview queries are capped at 100 rows
Custom queries are capped at 5000 rows
Query execution timeout defaults to 30 seconds and is configurable via MYSQL_QUERY_TIMEOUT_MS
Sensitive credentials are sanitized in error messages