Pydantic Ai Agent Creation

This walks you through spinning up PydanticAI agents with proper type safety and structured outputs. You get model selection across OpenAI, Anthropic, Google, and others using a simple provider:model-name format, plus Pydantic models for validated responses instead of raw strings. The dependency injection pattern is clean (deps_type lets you thread API keys or database connections through without globals), and the three verification gates at the end are genuinely useful for catching issues before production. If you're building anything beyond one-off LLM calls, the structured output alone justifies the setup cost. The instructions versus system prompts distinction trips people up initially, but the examples make it clear.

skills.sh installs: 219
GitHub stars: 87
last updated: Aug 21, 2026

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Install

$ npx -y skills add existential-birds/beagle --skill pydantic-ai-agent-creation --agent claude-code

Installs into .claude/skills of the current project.

Files

Creating PydanticAI Agents

Quick Start

from pydantic_ai import Agent

# Minimal agent (text output)
agent = Agent('openai:gpt-4o')
result = agent.run_sync('Hello!')
print(result.output)  # str

Model Selection

Model strings follow provider:model-name format:

# OpenAI
agent = Agent('openai:gpt-4o')
agent = Agent('openai:gpt-4o-mini')

# Anthropic
agent = Agent('anthropic:claude-sonnet-4-5')
agent = Agent('anthropic:claude-haiku-4-5')

# Google
agent = Agent('google-gla:gemini-2.0-flash')
agent = Agent('google-vertex:gemini-2.0-flash')

# Others: groq:, mistral:, cohere:, bedrock:, etc.

Structured Outputs

Use Pydantic models for validated, typed responses:

from pydantic import BaseModel
from pydantic_ai import Agent

class CityInfo(BaseModel):
    city: str
    country: str
    population: int

agent = Agent('openai:gpt-4o', output_type=CityInfo)
result = agent.run_sync('Tell me about Paris')
print(result.output.city)  # "Paris"
print(result.output.population)  # int, validated

Agent Configuration

from pydantic_ai import Agent
from pydantic_ai.settings import ModelSettings

SKILL.md on GitHub

Details

Repository: github.com/existential-birds/beagle
Categories: AI & Agent Building, Python
First seen: Jun 3, 2026