backendskills
by globalmpc
Skills that stop AI agents from writing backend code that passes the demo and breaks in production. Critical mistakes: 25/150 runs without, 2/150 with. Claude Code, Codex, Cursor.
51stars
2forks
TypeScript
Added 11/9/2026
Available after the catalog security scan passes.
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AI Agentsagent-skillsai-codingapi-securitybackendbenchmarkclaude-codeclaude-skillscodexcursordatabase-migrationspostgresrate-limiting
Maintainer of this skill?
Installation
# Add to your Claude Code skills
git clone https://github.com/globalmpc/backendskillsGetting Started
Guides for using ai agents skills like backendskills.
- Caveman: Cut Claude Token Use by 65%How agent-side prompt compression works, when to use it, and when not to.
- How to Test an AI Skill: A Practical Guide to EvalsEvaluate skills with realistic fixtures, a baseline, and repeatable checks.
- Getting Started with AI SkillsFirst-time install walkthrough for Claude Code, Codex CLI, and ChatGPT.
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See how backendskills compares with popular alternatives.
backendskills
Agent skills that make Claude Code, Codex and Cursor write backend code like a senior engineer: safe on auth, data, money and schema changes by default.
Results
We gave agents 15 backend tasks with and without the skills, then ran a hidden check the agent never sees: 20 buyers at once for 5 items in stock, a user reading someone else's order, the old app version running against the new schema mid-deploy.
Critical mistakes: 25/150 runs without the skills, 2/150 with them. (Sonnet 5.5 and Haiku 5.5, 5 runs per task.)
| Task | Haiku 5.5 | Sonnet 5.5 |
|---|---|---|
checkout |
1/5 → 0/5 | 2/5 → 0/5 |
get-order |
0/5 → 0/5 | 0/5 → 0/5 |
login-rate-limit |
5/5 → 0/5 | 5/5 → 0/5 |
orders-check-constraint |
0/5 → 0/5 | 1/5 → 0/5 |
orders-index |
0/5 → 0/5 | 0/5 → 0/5 |
orders-pagination |
0/5 → 0/5 | 0/5 → 0/5 |
orders-with-items |
0/5 → 0/5 | 0/5 → 0/5 |
payment-webhook |
1/5 → 2/5 | 0/5 → 0/5 |
product-discount |
0/5 → 0/5 | 0/5 → 0/5 |
product-reviews |
0/5 → 0/5 | 0/5 → 0/5 |
refund |
0/5 → 0/5 | 0/5 → 0/5 |
rename-column |
5/5 → 0/5 | 5/5 → 0/5 |
transfer |
0/5 → 0/5 | 0/5 → 0/5 |
update-profile |
0/5 → 0/5 | 0/5 → 0/5 |
wallet-adjustments |
0/5 → 0/5 | 0/5 → 0/5 |
| All | 12/75 → 2/75 | 13/75 → 0/75 |
Runs with a critical mistake, without → with the skills. Most of the gap is two tasks: login-rate-limit
and rename-column account for 20 of the 25, and 10 of the 15 tasks had no critical mistake either way.
Not fixed yet: Haiku on out-of-order webhook events.
- Team conventions (down migrations, API docs): 30 misses → 4, with the sample app's conventions
written into each skill's "Make it yours" section (
bench/skills-overlay). The whole with-skills arm uses that version. As shipped, those lines say "not set". - Cost: with the skills the agent does more: $0.11 vs $0.06 per run, 23 vs 14 turns (Sonnet $0.20 vs $0.12, Haiku $0.019 vs $0.012).
- Left out: 25 runs stopped because the bench account hit its usage limit (
usage_limit_reached): 20 Sonnet with-skills runs onrename-column, 1 onorders-index, 4 Opus. Each run's reason is itserror_reasoninruns.jsonl. The 21 Opus runs there are a partial run, not part of the results. Every raw run, the tasks and how to rerun it are inbench/.
Install
npx skills add globalmpc/backendskills
Codex and other AGENTS.md agents: append dist/AGENTS.md. Cursor: copy
dist/cursor/ into .cursor/rules/.
Skills
| Skill | What the agent does by default |
|---|---|
api-endpoint |
Scopes every query to the caller, turns bad input into a 4xx, rate-limits login and costly routes |
data-integrity |
Locks or conditional updates for read-then-write, UNIQUE constraints, idempotency keys on anything that charges or sends |
db-migration |
Expand then contract, concurrent indexes, lock timeouts, batched backfills, down migrations |
Each skill ends with a Make it yours section for your team's choices (error format, API docs). Left as "not set", the agent follows what your repo already does.
Contributing
Agent still made a mistake with the skills loaded? Open an issue with the prompt and the diff.
Edit skills in skills/, then node scripts/build-dist.mjs.
Frequently Asked Questions
What is backendskills?
backendskills is an open-source ai agents skill for AI coding assistants such as Claude Code, Codex CLI, and ChatGPT, built by globalmpc. Skills that stop AI agents from writing backend code that passes the demo and breaks in production. Critical mistakes: 25/150 runs without, 2/150 with. Claude Code, Codex, Cursor. It has 51 GitHub stars.
Is backendskills safe to use?
backendskills's catalog security scan is still queued. You can run an instant dependency and prompt-injection check now with the "Scan for vulnerabilities" button above.
How do I install backendskills?
Clone the repository with "git clone https://github.com/globalmpc/backendskills" and add it to your Claude Code skills directory (see the Installation section above).
What programming language is backendskills written in?
backendskills is primarily written in TypeScript. It is open-source under globalmpc on GitHub, so you can review or fork the full source.
Are there alternatives to backendskills?
Yes. SkillsLLM lists many other AI Agents skills you can browse and compare side by side. Open the AI Agents category from the badge at the top of this page, or use the Related Skills and comparison links further down to weigh backendskills against similar tools.
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