fastapi-expert

An agent skill by Jeffallan, from Jeffallan/claude-skills. Tags: api, automation, documentation, fastapi, python, web.

What it does

Use when building high-performance async Python APIs with FastAPI and Pydantic V2. Invoke to create REST endpoints, define Pydantic models, implement authentication flows, set up async SQLAlchemy database operations, add JWT authentication, build WebSocket endpoints, or generate OpenAPI documentation. Trigger terms: FastAPI, Pydantic, async Python, Python API, REST API Python, SQLAlchemy async, JWT authentication, OpenAPI, Swagger Python.

Install

With the skills CLI, which installs into Claude Code, Codex, Cursor and other agents:

npx skills add Jeffallan/claude-skills --skill fastapi-expert

Or copy the skill folder into Claude Code's skills directory by hand (~/.claude/skills for every project, or .claude/skills inside one):

git clone --depth 1 https://github.com/Jeffallan/claude-skills
cp -r claude-skills/skills/fastapi-expert ~/.claude/skills/fastapi-expert

Safety box score

Grade B, low risk: 21 of 100 risk points, rated 2026-10-17. The grade rates what the skill and its scripts can reach on the machine of whoever installs it, across eight categories from shell execution to secrets access. How the score works.

This skill is a FastAPI implementation guide: it generates Pydantic models, async SQLAlchemy code, JWT auth, routers, and async tests. The main risks are handling secrets via `.env`/JWT settings, and the fact that its examples include local test-database writes plus destructive CRUD and migration-cutover patterns.

Category levels, from 0 (none) to 3 (high)
Category	Level	Why
Code & shell execution	0 (none)	No shell scripts, code runners, or executable installers ship with the skill; the files are plain Markdown examples only.
Network access	0 (none)	It does not instruct downloading from or sending data to remote hosts; the only remote URLs are documentation/reference links.
Filesystem reach	1 (low)	The testing guide uses a local SQLite path (`sqlite+aiosqlite:///./test.db`) and the examples create/drop project files and tables, but nothing targets system paths.
Secrets & credentials	2 (moderate)	The settings example loads `env_file=".env"` and the auth snippets manage `SECRET_KEY`, JWTs, and password hashes, so using the skill puts environment secrets and credentials in scope.
Privilege & persistence	0 (none)	There is no sudo, global install, service registration, shell startup edit, or OS setting change in the shipped files.
Instruction hijack surface	0 (none)	I found no hidden prompts, prompt-override text, or instructions to ignore higher-priority rules or fetch untrusted instructions.
Irreversible actions	1 (low)	The skill includes CRUD delete endpoints and migration/cutover guidance like `Decommission Django`, but it does not itself execute those actions.
Transparency	1 (low)	It cross-references an unreviewed external file (`../legacy-modernizer/references/migration-strategies.md`), so some guidance is outside the audited bundle.

Before installing

Review `references/pydantic-v2.md` to confirm `.env` loading is acceptable in your environment.
Run the test setup in a scratch workspace first and check whether `./test.db` is created or overwritten.
Inspect the migration section for any unreviewed external guidance before using it on a live service.

Rated 2026-10-17 by an automated review of 7 files from the skill's repository.

Source

Repository: Jeffallan/claude-skills (all skills from this repository)
Path: skills/fastapi-expert/SKILL.md
Branch: main
Updated: 2026-09-19

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