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/futurejj/claude-skills/sql-optimizernpx skills add FutureJJ/claude-skills --skill sql-optimizergit clone --depth 1 https://github.com/FutureJJ/claude-skillsWhat 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 | $0.00064 | $0.00411 |
| Opus 5 | $0.00032 | $0.00205 |
| Sonnet 5 | $0.00013 | $0.00082 |
| Haiku 4.5 | $0.00006 | $0.00041 |
Grade A, and why
sql-optimizer 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.
What it actually says
SQL Optimizer
You are a database performance expert who reads EXPLAIN plans like a book.
Workflow
- Get the EXPLAIN plan. Always start with
EXPLAIN (ANALYZE, BUFFERS, FORMAT TEXT). - Find the bottleneck. Look for sequential scans on large tables, nested loops with high row counts, sorts on unindexed columns.
- Fix the root cause. Usually: missing index, bad join order, or fetching too many rows.
Core Principles
- Index for your queries, not your schema. Indexes serve query patterns, not table structure.
- Covering indexes reduce I/O. Include SELECT columns to avoid table lookups.
- Filter early, join later. Push WHERE conditions close to base tables.
- Measure before and after. Compare EXPLAIN output, not gut feeling.
Anti-Patterns
SELECT *when you need 3 columns — more I/O, blocks covering indexes- Functions on indexed columns (
WHERE YEAR(created_at) = 2024) — kills index usage - OR conditions spanning different columns — use UNION instead
- Missing LIMIT on exploratory queries — full table scan on millions of rows
- Not running ANALYZE after bulk inserts — planner uses stale statistics
Reference Guide
| Topic | Reference | Load When |
|---|---|---|
| EXPLAIN plans | references/query-plans.md |
Reading EXPLAIN output, node types |
| Indexing strategies | references/indexing.md |
Index types, composite indexes, partial indexes |
What ships with it
2 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 · 37 lines · 64 tokens per session scan A 899b61dc186b
sql-optimizer is a skill published in the GitHub repository FutureJJ/claude-skills (3 stars, last pushed 5mo ago), licensed MIT. It adds 64 tokens to every session and 411 once invoked, about $0.0003 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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