Mysql

Execute read-only SQL queries against multiple MySQL databases. Use when: (1) querying MySQL databases, (2) exploring database schemas/tables, (3) running SELECT queries for data analysis, (4) checking database contents. Supports multiple database connections with descriptions for intelligent auto-selection. Blocks all write operations (INSERT, UPDATE, DELETE, DROP, etc.) for safety.From its SKILL.md

Install

npx -y skills add sanjay3290/ai-skills --skill mysql

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

2 things to look at

reads credentialsReads from 1 credential source: `connections.json`.
runs commandsInstructs the agent to run 7 commands, including `pip install -r requirements.txt` and 6 more.

What its file declares

Copied from the file, not written here

The file declares its own license as Apache-2.0. That is the author’s claim about this one file, and it is not the same thing as the license GitHub reports for the repository, which is listed with the other numbers below.

SKILL.md

4.0 KB, 870 tokens by cl100k_base, as published. Nobody here has run it

MySQL Read-Only Query Skill

Execute safe, read-only queries against configured MySQL databases.

Requirements

Python 3.8+
mysql-connector-python: pip install -r requirements.txt

Setup

Create connections.json in the skill directory or ~/.config/claude/mysql-connections.json.

Security: Set file permissions to 600 since it contains credentials:

chmod 600 connections.json

{
  "databases": [
    {
      "name": "production",
      "description": "Main app database - users, orders, transactions",
      "host": "db.example.com",
      "port": 3306,
      "database": "app_prod",
      "user": "readonly_user",
      "password": "your-password",
      "ssl_disabled": false
    }
  ]
}

Config Fields

Field	Required	Description
name	Yes	Identifier for the database (case-insensitive)
description	Yes	What data this database contains (used for auto-selection)
host	Yes	Database hostname
port	No	Port number (default: 3306)
database	Yes	Database name
user	Yes	Username
password	Yes	Password
ssl_disabled	No	Set to `true` to disable SSL (default: false)
ssl_ca	No	Path to CA certificate file
ssl_cert	No	Path to client certificate file
ssl_key	No	Path to client private key file

Usage

List configured databases

python3 scripts/query.py --list

Query a database

python3 scripts/query.py --db production --query "SELECT * FROM users LIMIT 10"

List tables

python3 scripts/query.py --db production --tables

Show schema

python3 scripts/query.py --db production --schema

Limit results

python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 100

Database Selection

Match user intent to database description:

User asks about	Look for description containing
users, accounts	users, accounts, customers
orders, sales	orders, transactions, sales
analytics, metrics	analytics, metrics, reports
logs, events	logs, events, audit

If unclear, run --list and ask user which database.

Safety Features

Read-only session: Connection uses MySQL SET SESSION TRANSACTION READ ONLY (primary protection)
Query validation: Only SELECT, SHOW, DESCRIBE, EXPLAIN, WITH queries allowed
Single statement: Multiple statements per query rejected
SSL support: Configurable SSL with CA, client cert, and key support
Query timeout: 30-second max_execution_time enforced (MySQL 5.7.8+)
Memory protection: Max 10,000 rows per query to prevent OOM
Column width cap: 100 char max per column for readable output
Credential sanitization: Error messages don't leak passwords

Troubleshooting

Error	Solution
Config not found	Create `connections.json` in skill directory
Authentication failed	Check username/password in config
Connection timeout	Verify host/port, check firewall/VPN
SSL error	Try `"ssl_disabled": true` for local databases
Permission warning	Run `chmod 600 connections.json`
max_execution_time not supported	Upgrade to MySQL 5.7.8+ or MariaDB 10.1.1+

Exit Codes

0: Success
1: Error (config missing, auth failed, invalid query, database error)

Workflow

Run --list to show available databases
Match user intent to database description
Run --tables or --schema to explore structure
Execute query with appropriate LIMIT

What ships with it: 5 files

13.3 KB alongside SKILL.md, 1 of them executable

scripts/

query.pyruns10.1 KB

Gives 0 of the 12 instructions most databases sql skills give in 870 tokens

Counted across 609 of the 712 authors here whose files we hold, read 2026-09-06

Index all foreign key columnsin 26 of 609
Use cursor pagination instead of offsetin 25 of 609, across 20 files
Use timestamptz for timestampsin 21 of 609
Specify columns instead of using select starin 20 of 609, across 10 files
Use parameterized queries for all database interactionsin 20 of 609, across 19 files
Use Enum for categorical datain 17 of 609, across 7 files
Order by frequently filtered columnsin 17 of 609, across 7 files
Batch data insertsin 17 of 609, across 7 files
Use expand-contract pattern for schema changesin 17 of 609
Use materialized views for real-time aggregationsin 16 of 609, across 6 files
Partition tables by timein 16 of 609, across 6 files
Use smallest appropriate data typesin 16 of 609, across 6 files

Said here and by no other author read

Set file permissions to 600 for connection files
List available databases to identify the correct target
Match user intent to database descriptions
Explore database structure using tables or schema flags
Execute queries using the query flag
Ask the user if database selection is unclear

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.