Installation and setup

Pydantic AI installs as a slim core plus one extra per model provider. Groq and Gemini each have an extra and a free key.

pydantic-ai-slim[openai], pydantic-evals and pytest

pydantic-ai-slim is the framework without provider libraries; [openai] adds OpenAI's. The full pydantic-ai package installs every provider at once. pydantic-evals is for lesson 22 and pytest for lesson 21.

pip install "pydantic-ai-slim[openai]==2.43.0" "pydantic-evals==2.43.0" pytest

Example

from importlib.metadata import version

print(version("pydantic-ai-slim"))

Provider extras and model stringsOptional

The course runs on the built-in test model and a function model you write in lesson 4, so it needs no key. Lesson 6 moves to real providers: add the provider's extra, set its key and name the model.

python

from pydantic_ai import Agent

agent = Agent("groq:openai/gpt-oss-120b", instructions="You answer support tickets.")

Provider	Key	Variable	Extra and model string
Groq	Free, console.groq.com/keys	`GROQ_API_KEY`	`[groq]`, `"groq:openai/gpt-oss-120b"`
Gemini	Free, aistudio.google.com/apikey	`GOOGLE_API_KEY`	`[google]`, `"google:gemini-2.5-flash"`
OpenRouter	Free models end in `:free`, openrouter.ai/keys	`OPENROUTER_API_KEY`	`[openrouter]`, `"openrouter:google/gemma-4-31b-it:free"`
OpenAI	Paid, platform.openai.com/api-keys	`OPENAI_API_KEY`	`[openai]`, `"openai:gpt-5.2"`

pip install "pydantic-ai-slim[groq]==2.43.0"

export GROQ_API_KEY=gsk_...

Try it yourself

Create the agent above with no key set and read the error message.

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