What is mongo-migration?

A safety review and planning procedure for MongoDB schema changes, such as adding fields, changing indexes, or updating document types. MongoDB is a database that stores records as flexible documents rather than rows in tables.

Use it to review or plan MongoDB migrations, index operations, schema-validator changes, shard-key changes, and bulk updates to production data.

It helps reduce the risk of data loss, downtime, locking, or incompatible application changes during production migrations. It also accounts for MongoDB version support and large collections.

mongo-migration — Skill for Claude Code and Codex by johnqtcg

Install

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.

Any agent

npx skills add johnqtcg/awesome-skills --skill mongo-migration

Clone the repo

git clone --depth 1 https://github.com/johnqtcg/awesome-skills

Made for: Claude Code, Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/johnqtcg/awesome-skills/mongo-migration/github.svg)](https://agentmods.dev/skills/johnqtcg/awesome-skills/mongo-migration)

Your own site

<a href="https://agentmods.dev/skills/johnqtcg/awesome-skills/mongo-migration"><img src="https://agentmods.dev/badge/skills/johnqtcg/awesome-skills/mongo-migration/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/johnqtcg/awesome-skills/mongo-migration"><img src="https://agentmods.dev/badge/skills/johnqtcg/awesome-skills/mongo-migration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 140 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 5,410 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Excessive Agency · line 161
Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

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	$0.00140	$0.05410
Opus 5	$0.00070	$0.02705
Sonnet 5	$0.00028	$0.01082
Haiku 4.5	$0.00014	$0.00541

Measured 12d ago against content hash 180668b4be05, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

mongo-migration 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 12d ago.

The scan reads SKILL.md. This mod also ships 12 executable files (scripts/lint_migration.py, scripts/mongo_server_harness.sh, scripts/mutation_sweep.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/mongo-migration/SKILL.md · 369 lines

How it starts

The opening of the file, as written. The whole thing — 369 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MongoDB Migration Safety Review

Quick Reference

If you need to…	Go to
Understand what this skill covers	§1 Scope
Check mandatory prerequisites	§2 Mandatory Gates
Choose review depth	§3 Depth Selection
Handle incomplete context	§4 Degradation Modes
Analyze migration safety item by item	§5 Migration Safety Checklist
Design a phased execution plan	§6 Execution Plan
Avoid common migration mistakes	§7 Anti-Examples
Score the review result	§8 Scorecard
Format review output	§9 Output Contract
Look up index/DDL lock behavior	`references/mongo-ddl-lock-matrix.md`
Plan a large-collection migration	`references/large-collection-migration.md`

§1 Scope

In scope — schema migration safety for MongoDB 7.0 and 8.0, the releases still in support as of 2026-08. 4.4, 5.0 and 6.0 have reached end of life; if a user names one, say so before reviewing, because an EOL server receives no security fixes and the version-gated advice below assumes 7.0+:

Document schema evolution (add/remove/rename/retype fields)
Index operations (createIndex, dropIndex, replicated vs rolling builds, TTL indexes)
Schema validator changes (collMod with JSON Schema validation)
Data backfill and transformation (aggregation pipeline updates, bulkWrite)
Shard key changes (reshardCollection 5.0+, refineCollectionShardKey 4.4+)
Migration script review (mongosh scripts, application-driven migrations)
Write concern / read concern tuning during migration phases
Rollback planning (MongoDB's DDL is mostly non-transactional — but see §5.3 item 10: createCollection and createIndex do work inside a transaction)

Read the full file on GitHub · 369 lines

Files

What ships with it

29 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.

Changes

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.

12d ago First seen · 369 lines · 140 tokens per session scan A 180668b4be05

Subscribe to this mod's changes

mongo-migration is a skill published in the GitHub repository johnqtcg/awesome-skills (30 stars, last pushed yesterday), licensed MIT. It adds 140 tokens to every session and 5,410 once invoked, about $0.0007 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 2026-08-30.

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