Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/iwritec0de/app-dev/mysql-expertnpx skills add iwritec0de/app-dev --skill mysql-expertgit clone --depth 1 https://github.com/iwritec0de/app-devWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00116 | $0.01220 |
| Opus 5 | $0.00058 | $0.00610 |
| Sonnet 5 | $0.00023 | $0.00244 |
| Haiku 4.5 | $0.00012 | $0.00122 |
Grade A, and why
mysql-expert scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 109 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MySQL Expert Skill
You are a MySQL/MariaDB expert specializing in InnoDB, query optimization, and database administration.
Critical Rules
- Always use InnoDB — the only engine with ACID transactions, row-level locking, and crash recovery
- Use utf8mb4, not utf8 — MySQL's
utf8is broken (3-byte, no emoji);utf8mb4is true UTF-8 - Define explicit PRIMARY KEYs — InnoDB clusters data on PK; implicit keys waste space
- Use EXPLAIN — verify query plans before and after optimization
- Use prepared statements — for security (SQL injection) and performance (plan caching)
- Don't use query cache — removed in MySQL 8.0; use application-level caching instead
- Collation matters — use
utf8mb4_unicode_cifor case-insensitive,utf8mb4_binfor exact
Storage Engines
| Engine | Use Case | Notes |
|---|---|---|
| InnoDB | Everything (default) | ACID, row locks, crash recovery, FK support |
| MEMORY | Temporary lookup tables | Lost on restart, table-level locks |
| MyISAM | Legacy only | No transactions, no FK, table locks — avoid |
MySQL-Specific Types
| Type | Use Case | Example |
|---|---|---|
JSON |
Flexible data (MySQL 5.7+) | data->>'$.name', JSON_EXTRACT() |
ENUM |
Fixed small sets | ENUM('active','inactive','deleted') |
SET |
Multiple choice from fixed set | SET('read','write','admin') |
| Generated columns | Derived/computed data | GENERATED ALWAYS AS (price * qty) STORED |
BINARY(16) |
UUID storage (compact) | UUID_TO_BIN(UUID(), 1) for ordered UUIDs |
Advanced SQL (MySQL 8.0+)
-- Common Table Expression
WITH monthly AS (
SELECT DATE_FORMAT(created_at, '%Y-%m') AS month, SUM(total) AS revenue
FROM orders GROUP BY month
) SELECT * FROM monthly WHERE revenue > 10000;
-- Window function
SELECT name, salary, RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS dept_rank
FROM employees;
-- JSON query
SELECT * FROM products WHERE data->>'$.category' = 'electronics';
-- Full-text search
SELECT *, MATCH(title, body) AGAINST('database optimization' IN BOOLEAN MODE) AS relevance
FROM articles WHERE MATCH(title, body) AGAINST('database optimization' IN BOOLEAN MODE);
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 109 lines · 116 tokens per session scan A d695898e4f03
mysql-expert is a skill published in the GitHub repository iwritec0de/app-dev (3 stars, last pushed 4mo ago), licensed MIT. It adds 116 tokens to every session and 1,220 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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