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 skills add ericrisco/rsc-harness --skill mysqlgit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ericrisco/rsc-harness/mysql)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/mysql"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/mysql/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/mysql"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/mysql.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What 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 5.1 | $0.00116 | $0.04037 |
| Opus 5 | $0.00058 | $0.02018 |
| Sonnet 5 | $0.00023 | $0.00807 |
| Haiku 4.5 | $0.00012 | $0.00404 |
Grade A, and why
mysql 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 5d 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 — 250 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MySQL / MariaDB engine
You are working below portable SQL, at the layer where the answer depends on which engine is
running. This skill owns MySQL 8.4 LTS and MariaDB 11.8 LTS: the InnoDB clustered-index storage
model, MySQL-flavoured DDL and types, index design and the leftmost-prefix rule, reading EXPLAIN
and fixing the plan, online DDL, replication, locking/deadlocks, and day-2 server config.
The dividing line is simple: if the answer is identical on PostgreSQL, it belongs in sql, not
here. sql owns the dialect-independent SELECT grammar. mysql owns how this engine stores,
plans, locks, and replicates. postgresdb is the peer engine for the other database — same body
shape, different facts, never the same answer.
When to use
- Designing or reviewing a MySQL/MariaDB schema: engine choice, integer/
DECIMAL/VARCHARsizing,utf8mb4charset/collation,JSON+ generated/STOREDcolumns, PK design for InnoDB. - A query is slow or scans too many rows; reading
EXPLAIN/EXPLAIN ANALYZE/FORMAT=JSON. - Choosing or adding an index: composite column order, covering indexes, prefix indexes on
TEXT, invisible indexes for safe rollout, why an index is not used. - Schema change on a large/hot table without downtime:
ALGORITHM=INSTANT/INPLACE/COPY, pt-osc, gh-ost. - Replication: binlog row format, GTID (incl. tagged GTIDs), replica lag, semi-sync, group replication.
- Locking/concurrency: deadlocks, gap/next-key locks,
REPEATABLE READ,SELECT ... FOR UPDATE. - Operating the server: buffer pool,
caching_sha2_password+ TLS, slow-query log,performance_schema. - Migrating 5.7/8.0 → 8.4 LTS, or reasoning about MySQL ↔ MariaDB divergence.
When NOT to use
| The ask | Goes to |
|---|---|
| Portable query craft — joins, window functions, CTEs, NULL 3VL | sql |
| PostgreSQL engine behaviour — MVCC, VACUUM, RLS, JSONB, PgBouncer | postgresdb |
| PlanetScale / Vitess branch + deploy-request workflow, no-FK design | planetscale |
| Vendor-neutral migration theory — expand-contract, batched backfill | db-migrations |
| ORM / query-builder API ergonomics | drizzle-orm, prisma-orm |
| Backup strategy / retention / restore drills as a discipline | backups |
| OLAP / columnar analytics | clickhouse-analytics, duckdb |
What ships with it
7 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.
- 5d ago First seen · 250 lines · 116 tokens per session scan A a2769fab7a6b
mysql is a skill published in the GitHub repository ericrisco/rsc-harness (70 stars, last pushed yesterday), licensed MIT. It adds 116 tokens to every session and 4,037 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 2026-09-03.
Other skills, from other repositories
mysql-expert
MySQL and MariaDB administration and development: InnoDB internals, indexing, query tuning, replication, and online schema change. Use when the user mentions MySQL, MariaDB, InnoDB, my.cnf, slow queries, EXPLAIN, binlog or replication lag, gtid, Percona or pt-online-schema-change, or when the task involves designing a…
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dev-supabase
Backend development with Supabase. Trigger when the user wants to configure auth, the database, or Supabase storage.
dev-prisma
Development with Prisma ORM (schema, migrations, type-safe queries, Accelerate, transactions). Trigger when the user wants to add a model, create a migration, optimize Prisma queries, or when schema.prisma is detected in the project.
ops-database
Database schema design. Trigger when the user wants to create tables, migrations, or optimize queries.