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 bcastelino/agent-skills-kit --skill nosql-expertgit clone --depth 1 https://github.com/bcastelino/agent-skills-kitWrote 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/bcastelino/agent-skills-kit/nosql-expert)<a href="https://agentmods.dev/skills/bcastelino/agent-skills-kit/nosql-expert"><img src="https://agentmods.dev/badge/skills/bcastelino/agent-skills-kit/nosql-expert/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/bcastelino/agent-skills-kit/nosql-expert"><img src="https://agentmods.dev/badge/skills/bcastelino/agent-skills-kit/nosql-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00042 | $0.01442 |
| Opus 5 | $0.00021 | $0.00721 |
| Sonnet 5 | $0.00008 | $0.00288 |
| Haiku 4.5 | $0.00004 | $0.00144 |
Grade A, and why
nosql-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 11d 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.
This is a copy
95% identical to nosql-expert — 8 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.
NoSQL Expert Patterns (Cassandra & DynamoDB)
Overview
This skill provides professional mental models and design patterns for distributed wide-column and key-value stores (specifically Apache Cassandra and Amazon DynamoDB).
Unlike SQL (where you model data entities), or document stores (like MongoDB), these distributed systems require you to model your queries first.
When to Use
- Designing for Scale: Moving beyond simple single-node databases to distributed clusters.
- Technology Selection: Evaluating or using Cassandra, ScyllaDB, or DynamoDB.
- Performance Tuning: Troubleshooting "hot partitions" or high latency in existing NoSQL systems.
- Microservices: Implementing "database-per-service" patterns where highly optimized reads are required.
The Mental Shift: SQL vs. Distributed NoSQL
| Feature | SQL (Relational) | Distributed NoSQL (Cassandra/DynamoDB) |
|---|---|---|
| Data modeling | Model Entities + Relationships | Model Queries (Access Patterns) |
| Joins | CPU-intensive, at read time | Pre-computed (Denormalized) at write time |
| Storage cost | Expensive (minimize duplication) | Cheap (duplicate data for read speed) |
| Consistency | ACID (Strong) | BASE (Eventual) / Tunable |
| Scalability | Vertical (Bigger machine) | Horizontal (More nodes/shards) |
The Golden Rule: In SQL, you design the data model to answer any query. In NoSQL, you design the data model to answer specific queries efficiently.
Core Design Patterns
1. Query-First Modeling (Access Patterns)
You typically cannot "add a query later" without migration or creating a new table/index.
Process:
- List all Entities (User, Order, Product).
- List all Access Patterns ("Get User by Email", "Get Orders by User sorted by Date").
- Design Table(s) specifically to serve those patterns with a single lookup.
2. The Partition Key is King
Data is distributed across physical nodes based on the Partition Key (PK).
- Goal: Even distribution of data and traffic.
- Anti-Pattern: Using a low-cardinality PK (e.g.,
status="active"orgender="m") creates Hot Partitions, limiting throughput to a single node's capacity. - Best Practice: Use high-cardinality keys (User IDs, Device IDs, Composite Keys).
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.
- 11d ago First seen · 112 lines · 42 tokens per session scan A d67395b4ebcf
nosql-expert is a skill published in the GitHub repository bcastelino/agent-skills-kit (2 stars, last pushed 1mo ago), licensed MIT. It adds 42 tokens to every session and 1,442 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to nosql-expert, differing in 8 lines, and is treated as a copy.
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