Flask Agent Skill

by microsoft

Best practices for Flask web development including routing, blueprints, and testing.

432 tokens

context cost

the whole folder, loaded on every use

files

instructions only

copies elsewhere

how many repositories repackaged it

2448

stars on the repo

on the repository, not the skill itself

Install

one command, takes just this skill from the repository

npx skills add https://github.com/microsoft/debugpy --skill flask

The instruction itself

7 sections, as written by the author

Skill: Flask

Best practices for Flask web development including routing, blueprints, and testing.

When to Use

Apply this skill when building Flask web applications or APIs — routing, blueprints, extensions, and testing.

Project Structure

Use the application factory pattern (create_app()) to avoid global state and enable testing.
Organize features into Blueprints; register them in the factory.
Keep configuration in a config.py with classes like DevelopmentConfig, ProductionConfig.

Routing and Views

Prefer explicit HTTP method decorators (@app.get, @app.post) over generic @app.route with methods=[...].
Validate request data early; return 400 errors for malformed input before processing.
Use flask.abort() with appropriate HTTP codes rather than returning error responses manually.

Extensions

Initialize extensions lazily with ext.init_app(app) inside the factory, not at module level.
Common extensions: Flask-SQLAlchemy, Flask-Migrate, Flask-Login, Flask-WTF, Flask-CORS.

Testing

Use app.test_client() for HTTP-level tests and app.test_request_context() for unit tests.
Use pytest fixtures to create the app and client; scope appropriately (session for the app, function for the client).
Set TESTING=True and use a separate test database.

Pitfalls

Never use the development server (app.run()) in production — use Gunicorn or uWSGI.
Avoid storing mutable state on the app object; use g for request-scoped data.
Never hardcode SECRET_KEY — load from environment variables.

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How to use it

Copy the folder

Take microsoft/flask from the repository into ~/.claude/skills for personal use, or into .claude/skills inside a project.

Check the name does not clash

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