fastapi-function-definitions

fastapi-function-definitions is a cursor rule for Cursor from paulpham157/paul-s-cursor-rules. It costs 0 tokens per session (67 once invoked), scanned A, original, MIT.

A FastAPI guideline for choosing between regular and asynchronous Python functions and for using type hints and Pydantic models in routes.

In plain words
What is it for?
Use it when writing FastAPI router functions, especially those that perform asynchronous operations.
Why use it?
It helps match function definitions to the work they perform and makes route inputs easier to validate and understand.

Cursor rule for Cursor

Written for Cursor: a Cursor rule (.mdc).

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.

agentmods
npx agentmods add rules/paulpham157/paul-s-cursor-rules/fastapi-function-definitions
Clone the repo
git clone --depth 1 https://github.com/paulpham157/paul-s-cursor-rules

Made for: Cursor.

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.

agentmods badge for fastapi-function-definitions

README.md
[![agentmods](https://agentmods.dev/badge/rules/paulpham157/paul-s-cursor-rules/fastapi-function-definitions.svg)](https://agentmods.dev/rules/paulpham157/paul-s-cursor-rules/fastapi-function-definitions)
Your own site
<a href="https://agentmods.dev/rules/paulpham157/paul-s-cursor-rules/fastapi-function-definitions"><img src="https://agentmods.dev/badge/rules/paulpham157/paul-s-cursor-rules/fastapi-function-definitions.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 67 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00067
Opus 5 $0.00000 $0.00034
Sonnet 5 $0.00000 $0.00013
Haiku 4.5 $0.00000 $0.00007

Measured 2d ago against content hash eaa337036d3a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

fastapi-function-definitions 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 2d 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.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

1/framework_rules/rules/cursorrules-file-cursor-ai-python-fastapi-api/fastapi-function-definitions.mdc · 6 lines

What it actually says


description: Specifies the use of 'def' and 'async def' for function definitions within FastAPI routers. globs: **/routers/*.py

  • Use def for pure functions and async def for asynchronous operations.
  • Use type hints for all function signatures. Prefer Pydantic models over raw dictionaries for input validation.
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.

  1. 2d ago First seen · 6 lines · 67 tokens per session scan A eaa337036d3a

Subscribe to this mod's changes

fastapi-function-definitions is a cursor rule published in the GitHub repository paulpham157/paul-s-cursor-rules (27 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 67 tokens. 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 2026-09-03.