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 agentmods add rules/mitas/cursor-rules/fastapigit clone --depth 1 https://github.com/mitas/cursor-rulesWhat 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 | $0.00421 | $0.00421 |
| Opus 5 | $0.00211 | $0.00211 |
| Sonnet 5 | $0.00084 | $0.00084 |
| Haiku 4.5 | $0.00042 | $0.00042 |
Grade A, and why
fastapi 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 yesterday.
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.
This is a copy
97% identical to fastapi — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
What it actually says
description: FastAPI best practices and patterns for building modern Python web APIs globs: /*.py, app//.py, api/**/.py
FastAPI Best Practices
Project Structure
- Use proper directory structure
- Implement proper module organization
- Use proper dependency injection
- Keep routes organized by domain
- Implement proper middleware
- Use proper configuration management
API Design
- Use proper HTTP methods
- Implement proper status codes
- Use proper request/response models
- Implement proper validation
- Use proper error handling
- Document APIs with OpenAPI
Models
- Use Pydantic models
- Implement proper validation
- Use proper type hints
- Keep models organized
- Use proper inheritance
- Implement proper serialization
Database
- Use proper ORM (SQLAlchemy)
- Implement proper migrations
- Use proper connection pooling
- Implement proper transactions
- Use proper query optimization
- Handle database errors properly
Authentication
- Implement proper JWT authentication
- Use proper password hashing
- Implement proper role-based access
- Use proper session management
- Implement proper OAuth2
- Handle authentication errors properly
Security
- Implement proper CORS
- Use proper rate limiting
- Implement proper input validation
- Use proper security headers
- Handle security errors properly
- Implement proper logging
Performance
- Use proper caching
- Implement proper async operations
- Use proper background tasks
- Implement proper connection pooling
- Use proper query optimization
- Monitor performance metrics
Testing
- Write proper unit tests
- Implement proper integration tests
- Use proper test fixtures
- Implement proper mocking
- Test error scenarios
- Use proper test coverage
Deployment
- Use proper Docker configuration
- Implement proper CI/CD
- Use proper environment variables
- Implement proper logging
- Use proper monitoring
- Handle deployment errors properly
Documentation
- Use proper docstrings
- Implement proper API documentation
- Use proper type hints
- Keep documentation updated
- Document error scenarios
- Use proper versioning
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.
- yesterday First seen · 86 lines · 421 tokens per session scan A 760095ae8fdd
fastapi is a cursor rule published in the GitHub repository mitas/cursor-rules (2 stars, last pushed 1y ago), licensed MIT. It adds 421 tokens to every session, about $0.0021 per session on Opus 5. A static security scan graded it A with 0 findings. It is 97% identical to fastapi, differing in 7 lines, and is treated as a copy.
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