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 ludo-technologies/python-best-practices --skill web-applicationgit clone --depth 1 https://github.com/ludo-technologies/python-best-practicesWrote 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/ludo-technologies/python-best-practices/web-application)<a href="https://agentmods.dev/skills/ludo-technologies/python-best-practices/web-application"><img src="https://agentmods.dev/badge/skills/ludo-technologies/python-best-practices/web-application/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/ludo-technologies/python-best-practices/web-application"><img src="https://agentmods.dev/badge/skills/ludo-technologies/python-best-practices/web-application.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 | $0.00112 | $0.02225 |
| Opus 5.5 | $0.00045 | $0.00890 |
| Sonnet 5.5 | $0.00022 | $0.00445 |
| Haiku 4.5 | $0.00011 | $0.00222 |
Grade A, and why
web-application 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 9d 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 — 228 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Python Web Application
Best practices for FastAPI backends. Designed for AI agents and LLMs to build web applications that are secure, correct under concurrency, and testable.
The rules assume one stack: FastAPI, SQLAlchemy 2.0 (async), Alembic, Pydantic v2 with pydantic-settings, httpx, PyJWT, and pwdlib. Examples use the async stack; the same rules apply to sync def endpoints with Session. Django and Flask are out of scope. Where a rule overlaps a coding-standards or testing rule, this skill takes precedence for web application code.
All examples share one invoice application. Its models are defined in db-sqlalchemy-2-style, its Settings in config-typed-settings, and its create_app in app-factory-lifespan; other rules show only the part they discuss. Read the matching rule file in full before writing code in its area.
Categories
Security [CRITICAL]
Authenticate users safely and authorize every access to their data.
| Rule | Description |
|---|---|
| sec-password-hashing | Hash passwords with Argon2 |
| sec-secure-tokens | Generate tokens with secrets and compare in constant time |
| sec-jwt-validation | Validate JWTs with a pinned algorithm and required claims |
| sec-object-authorization | Authorize access to every object, not just the endpoint |
| sec-cors-origins | List allowed CORS origins explicitly |
Database [CRITICAL]
Query, scope, and evolve the database safely with SQLAlchemy 2.0 and Alembic.
| Rule | Description |
|---|---|
| db-parameterized-queries | Never build SQL with string formatting |
| db-session-per-request | Create the engine once and a session per request |
| db-transaction-boundary | Commit once per use case, not in helpers or dependency teardown |
| db-eager-loading | Load relationships explicitly and make lazy loads raise |
| db-migrations-alembic | Change the schema with Alembic migrations |
| db-sqlalchemy-2-style | Use SQLAlchemy 2.0 typed models and select() |
What ships with it
26 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.
- metadata.json 1.2 KB
- README.md 6.2 KB
- rules/_sections.md 3.5 KB
- rules/_template.md 447 B
- rules/api-bounded-lists.md 3.3 KB
- rules/api-error-responses.md 4.5 KB
- rules/api-separate-schemas.md 3.6 KB
- rules/app-factory-lifespan.md 4.3 KB
- rules/app-thin-routes.md 4.1 KB
- rules/async-no-blocking-calls.md 4.0 KB
- rules/async-shared-http-client.md 3.7 KB
- rules/config-typed-settings.md 3.5 KB
- rules/db-eager-loading.md 3.7 KB
- rules/db-migrations-alembic.md 3.4 KB
- rules/db-parameterized-queries.md 3.2 KB
- rules/db-session-per-request.md 4.0 KB
- rules/db-sqlalchemy-2-style.md 4.5 KB
- rules/db-transaction-boundary.md 4.0 KB
- rules/obs-request-id-logging.md 4.7 KB
- rules/sec-cors-origins.md 2.5 KB
- rules/sec-jwt-validation.md 4.3 KB
- rules/sec-object-authorization.md 3.6 KB
- rules/sec-password-hashing.md 3.6 KB
- rules/sec-secure-tokens.md 3.9 KB
- rules/test-db-rollback.md 4.9 KB
- rules/test-dependency-overrides.md 5.0 KB
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.
- 9d ago First seen · 228 lines · 112 tokens per session scan A 272a6ba596e4
web-application is a skill published in the GitHub repository ludo-technologies/python-best-practices (34 stars, last pushed 9d ago), licensed MIT. It adds 112 tokens to every session and 2,225 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-10-21.
Other skills, from other repositories
build-mcp-server
This skill should be used when the user asks to "build an MCP server", "create an MCP", "make an MCP integration", "wrap an API for Claude", "expose tools to Claude", "make an MCP app", or discusses building something with the Model Context Protocol. It is the entry point for MCP server development — it interrogates…
data-manager-api-setup
Guides developers through client library installation and authentication setup steps for the Data Manager API. Use this skill when a user is getting started with the Data Manager API and needs to setup their local environment, install the client library, or setup access to the API. Don't use for implementing audience…
vss-manage-video-io-storage
Use to drive vss vios for sensor list, timelines, clips, snapshots, and add/delete of video or stream sources, and the VIOS REST API only for what that CLI does not cover (sensor info/status/settings, storage and recorder status, WebRTC, the RTSP proxy, network scan, device settings, bytes to disk, the NvStreamer…
workers-best-practices
Cloudflare Workers best practices for production applications. Use when writing, reviewing, or configuring Workers.
vss-search-archive
Use this skill when a user wants to search archived VSS video that is already registered in a configured deployment — by natural-language, similarity, attribute, object-ID, or lexical tag query. Not for fresh clip Q&A, live captioning, video summarization, deployment, or source ingestion/deletion.
new
Create a new project to start development quickly.