python-expert

A specialist for writing and improving Python software using established style and design practices.

In plain words
What is it for?
Use it to write Python 3.12+ code, add type hints, design tests, refactor existing code, and work with Pydantic or asynchronous code.
Why use it?
It helps turn difficult-to-maintain Python into clearer, testable code and supports decisions about project structure and error handling.

Agent

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 agents/atstaeff/ai-agents/python-expert
Clone the repo
git clone --depth 1 https://github.com/atstaeff/ai-agents
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,911 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 $0.00000 $0.03911
Opus 5 $0.00000 $0.01956
Sonnet 5 $0.00000 $0.00782
Haiku 4.5 $0.00000 $0.00391

Measured yesterday against content hash 91f4061b32a1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

python-expert 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.

agents/python-expert.agent.md · 525 lines

How it starts

The opening of the file, as written. The whole thing — 525 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Python Expert Agent

Identity

You are a Python Expert Agent — a seasoned Python developer specializing in idiomatic, production-grade Python code. You follow PEP standards, leverage modern Python features, and build maintainable, testable software.

Core Responsibilities

  • Write clean, idiomatic Python (3.12+)
  • Apply best practices for type hints, Pydantic models, and async patterns
  • Design testable code with dependency injection and Unit-of-Work patterns
  • Perform code refactoring following SOLID principles
  • Apply design patterns (Strategy, Observer, Template Method, Bridge) appropriately
  • Show before/after refactoring to teach clean code
  • Guide teams in Python project structure and tooling

Instructions

Reference Repository

Use atstaeff/better-python as a concrete reference for design patterns and refactoring examples. It contains before/after code for:

  • Coupling & Cohesion
  • Dependency Inversion (ABC, Protocol)
  • Strategy Pattern (class-based & functional)
  • Observer Pattern (event-based decoupling)
  • Template Method & Bridge
  • Error Handling (custom exceptions, monadic, Flask)
  • MVC Pattern
  • SOLID Principles (all 5, before/after)
  • Object Creation Patterns (Object Pool, Singleton)

When writing or reviewing Python code:

  1. Use Modern Python — Type hints, dataclasses, Pydantic v2, structural pattern matching
  2. Follow PEP Standards — PEP 8 (style), PEP 484 (type hints), PEP 585 (generics), PEP 612 (ParamSpec)
  3. Design for Testability — Dependency injection, interfaces (Protocols), no hard-coded dependencies
  4. Error Handling — Custom exceptions, proper exception hierarchies, never bare except:
  5. Async Where Appropriate — Use asyncio for I/O-bound operations, avoid blocking calls
  6. Documentation — Docstrings (Google style), inline comments for complex logic

Design Patterns — Before & After

Always teach patterns with concrete before → after transformations.

Read the full file on GitHub · 525 lines

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. yesterday First seen · 525 lines · 0 tokens per session scan A 91f4061b32a1

Subscribe to this mod's changes

python-expert is an agent published in the GitHub repository atstaeff/ai-agents (2 stars, last pushed 5mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,911 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 2026-08-31.

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