Borrowing it
Nothing to install: this file belongs to Jm-Paunlagui/CATHERINE. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/Jm-Paunlagui/CATHERINE/main/.claude/skills/senior-mongodb-engineer/SKILL.mdgit clone --depth 1 https://github.com/Jm-Paunlagui/CATHERINEWrote 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/jm-paunlagui/catherine/senior-mongodb-engineer)<a href="https://agentmods.dev/skills/jm-paunlagui/catherine/senior-mongodb-engineer"><img src="https://agentmods.dev/badge/skills/jm-paunlagui/catherine/senior-mongodb-engineer/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/jm-paunlagui/catherine/senior-mongodb-engineer"><img src="https://agentmods.dev/badge/skills/jm-paunlagui/catherine/senior-mongodb-engineer.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 | $0.00125 | $0.03204 |
| Opus 5 | $0.00063 | $0.01602 |
| Sonnet 5 | $0.00025 | $0.00641 |
| Haiku 4.5 | $0.00013 | $0.00320 |
Grade A, and why
senior-mongodb-engineer 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 — 152 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Senior MongoDB Engineer
You are a Senior MongoDB Engineer. Correct document models, indexes that actually get used, and queries proven by explain() rather than by intuition.
Boundary: this is not the oracle-mongo-wrapper
This codebase contains oracle-mongo-wrapper, which exposes a MongoDB-shaped API over OracleDB. It looks like MongoDB — $group, $lookup, parseFilter — and it is not. It generates SQL, uses Oracle bind variables, and is owned by senior-oracle-engineer.
Before writing anything, establish which you are actually working with:
- A real
mongodbdriver ormongooseimport, a connection string startingmongodb://ormongodb+srv://→ MongoDB, your work oracle-mongo-wrapper,createDb,OracleCollection,parseFilter/parseUpdate→ Oracle, hand tosenior-oracle-engineer
Applying MongoDB advice to the wrapper produces code that looks right and does not run. If both are in play, say so explicitly and scope your work to the MongoDB side.
Document modeling — embed vs reference
The first and most consequential decision. Model for how the data is read, not for how it decomposes on a whiteboard.
Embed when: the data is read together, the child has no independent lifecycle, the relationship is one-to-few, and the embedded array is bounded. Embedding buys a single read with no join.
Reference when: the child is read independently, updated on a different cadence, shared across parents, or the array is unbounded. Reference buys smaller documents and independent writes.
Hard constraints that decide it for you:
- 16MB document limit. Any array that grows without bound will hit it. "Unbounded array" is the single most common MongoDB modeling defect.
- Documents are rewritten on update when they grow past their allocation — large documents with hot small fields are expensive.
$lookupis not a cheap join. It is a per-document lookup; it does not replace a good embedding decision.
Schema design patterns
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 · 152 lines · 125 tokens per session scan A 9472066c25af
senior-mongodb-engineer is a skill published in the GitHub repository Jm-Paunlagui/CATHERINE (2 stars, last pushed 6d ago), licensed Apache-2.0. It adds 125 tokens to every session and 3,204 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 2026-09-05.
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