Pydantic AI

Pydantic AI is the Pydantic team's agent framework. It's provider-agnostic and reuses the Pydantic models you'd already validate API I/O with for tool arguments and final outputs, so adding an agent to a typed Python codebase doesn't introduce a parallel schema layer. The Steel integration passes a Playwright Page through RunContext.deps, so every tool in an agent run sees the same cloud browser without module globals.

Requirements

Steel API Key: Active Steel subscription
Model provider key: OpenAI, Anthropic, Google, or any other Pydantic AI-supported provider
Python: 3.10+

Connect Steel to Pydantic AI

Define a BrowserDeps dataclass holding the Steel-backed Playwright Page, register tools that read ctx.deps.page, and pass deps= to agent.run:

Python

from dataclasses import dataclass
from playwright.async_api import Page, async_playwright
from pydantic_ai import Agent, RunContext
from steel import Steel

@dataclass
class BrowserDeps:
    page: Page

async def navigate(ctx: RunContext[BrowserDeps], url: str) -> dict:
    """Navigate to a URL and wait for the page to load."""
    await ctx.deps.page.goto(url, wait_until="domcontentloaded")
    return {"url": ctx.deps.page.url, "title": await ctx.deps.page.title()}

agent = Agent(
    "openai:gpt-5-mini",
    deps_type=BrowserDeps,
    tools=[navigate],
)

steel = Steel(steel_api_key=STEEL_API_KEY)
session = steel.sessions.create()
playwright = await async_playwright().start()
browser = await playwright.chromium.connect_over_cdp(
    f"{session.websocket_url}&apiKey={STEEL_API_KEY}"
)
page = browser.contexts[0].pages[0]

result = await agent.run("Open example.com and report the title.", deps=BrowserDeps(page=page))

Full runnable starter: Steel + Pydantic AI recipe →

Resources

Pydantic AI documentation – Agents, tools, output validators, retries, and Logfire integration
Steel Sessions API reference – Programmatic session control for Steel browsers
Steel Discord – Get help and share what you build