pydantic-ai-skills: Instructions file for Claude Code

CLAUDE.md

pydantic-ai-skills CLAUDE.md is an instructions file for Claude Code from Fuenfgeld/pydantic-ai-skills. It costs 856 tokens per session, scanned A, original, MIT.

A set of development instructions for building applications with Pydantic AI, a Python framework for AI agents. It follows TDD, or test-driven development, which means writing tests before implementation.

In plain words
What is it for?
Use it to create plans and specifications, define input and output rules, write evaluation data and unit tests, build Pydantic models, add monitoring, and assess agent behavior.
Why use it?
It provides an ordered workflow for planning, documenting, testing, implementing, evaluating, and refining an agent.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions Claude Code.

This is Fuenfgeld/pydantic-ai-skills's own configuration. It tells Claude Code how to work on pydantic-ai-skills itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything pydantic-ai-skills configures →

Reuse

Borrowing it

Nothing to install: this file belongs to Fuenfgeld/pydantic-ai-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Fuenfgeld/pydantic-ai-skills/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/Fuenfgeld/pydantic-ai-skills

Made for: Claude Code.

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Per session 856 This file is loaded in full into every session.
When invoked 856 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00856 $0.00856
Opus 5 $0.00428 $0.00428
Sonnet 5 $0.00171 $0.00171
Haiku 4.5 $0.00086 $0.00086

Measured 12d ago against content hash ebeca397e49b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

pydantic-ai-skills CLAUDE.md 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 12d 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.

CLAUDE.md · 146 lines

How it starts

The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Core Principles

  • TDD (Test-Driven Development): Write tests before implementation
  • KISS (Keep It Simple, Stupid): Start simple, add complexity incrementally
  • SOLID Principles: Maintain clean, maintainable architecture
  • Evaluation-Driven Development: Treat evaluations as first-class code

Development Workflow

Plan → Document → Test → Implement → Evaluate → Refine

Phase 1: Plan

  • Review requirements for the feature/agent
  • Design high-level architecture
  • Identify evaluation strategies
  • Create implementation plan document in .claude/plan/ folder in the project folder
  • Plan must be updated regularly throughout implementation

Phase 2: Document

  • Write detailed specifications
  • Define input/output contracts
  • Document expected behavior
  • Create architecture decision records

Phase 3: Test (Write First!)

  • Create Pydantic Evals dataset with test cases
  • Implement custom evaluators if needed
  • Write traditional unit tests for utilities
  • Define success criteria

Phase 4: Implement

  • Build Pydantic models
  • Implement agent with proper patterns
  • Add Logfire instrumentation
  • Follow SOLID principles

Phase 5: Evaluate

  • Run evaluation suite
  • Analyze Logfire traces
  • Identify failures and edge cases
  • Iterate until tests pass

Phase 6: Refine

  • Document learnings
  • Update SKILL_IMPROVEMENTS.md
  • Refactor for clarity
  • Update documentation

Progress Plans

CRITICAL: All implementations MUST have a progress plan that is actively maintained.

Plan Requirements

  • Location: All plans must be stored in project directory .claude/plan/ directory
  • Format: Markdown files named descriptively (e.g., user-auth-agent.md, data-pipeline-refactor.md)
  • Updates: Plans must be updated regularly as implementation progresses
  • Content: Include:
    • Current status and phase
    • Completed tasks (with checkmarks)
    • In-progress tasks
    • Blockers or challenges
    • Next steps
    • Decision records

Read the full file on GitHub · 146 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. 12d ago First seen · 146 lines · 856 tokens per session scan A ebeca397e49b

Subscribe to this mod's changes

pydantic-ai-skills CLAUDE.md is an instructions file published in the GitHub repository Fuenfgeld/pydantic-ai-skills (10 stars, last pushed 2mo ago), licensed MIT. It adds 856 tokens to every session, about $0.0043 per session on Opus 5. 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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