TypeError when importing `duckduckgo_search_tool`

[jhammarstedt]

Initial Checks

• I confirm that I'm using the latest version of Pydantic AI
• I confirm that I searched for my issue in https://github.com/pydantic/pydantic-ai/issues before opening this issue

Description

Bug: TypeError when importing duckduckgo_search_tool

Description

Importing pydantic_ai.common_tools.duckduckgo.duckduckgo_search_tool raises a TypeError due to missing from __future__ import annotations.

Error

from pydantic_ai.common_tools.duckduckgo import duckduckgo_search_tool

TypeError: unsupported operand type(s) for |: '_DDGSLazyLoader' and 'NoneType'
  File "pydantic_ai/common_tools/duckduckgo.py", line 65, in <module>
    def duckduckgo_search_tool(duckduckgo_client: DDGS | None = None, max_results: int | None = None):

Root Cause

• ddgs package exports DDGS as a _DDGSLazyLoader instance (not a type)
• Type annotation DDGS | None evaluates at import time
• The lazy loader instance doesn't support the | operator

Fix

Add from __future__ import annotations to the top of pydantic_ai/common_tools/duckduckgo.py:

from __future__ import annotations

import functools
from dataclasses import KW_ONLY, dataclass
# ... rest of file

Impact

• Particularly problematic in Temporal workflows where imports occur during activity execution
• Causes immediate import failures in any code using the DuckDuckGo tool

Will open a PR with the fix and link it here

Example Code

import asyncio
from datetime import timedelta

from temporalio import activity, workflow
from temporalio.client import Client
from temporalio.worker import Worker

with workflow.unsafe.imports_passed_through():
    from pydantic_ai.common_tools.duckduckgo import duckduckgo_search_tool



@activity.defn
async def web_search_activity(query: str) -> list[dict]:
    """Same error get's throw in a DurableAgent as we try to make the same import"""
    
    tool = duckduckgo_search_tool(max_results=3)
    return await tool.function(query)


@workflow.defn
class SearchWorkflow:
    @workflow.run
    async def run(self, query: str) -> list[dict]:
        return await workflow.execute_activity(
            web_search_activity,
            query,
            start_to_close_timeout=timedelta(seconds=30),
        )


async def main():
    client = await Client.connect("localhost:7233")
    
    async with Worker(
        client,
        task_queue="test-duckduckgo-queue",
        workflows=[SearchWorkflow],
        activities=[web_search_activity],
    ):
        result = await client.execute_workflow(
            SearchWorkflow.run,
            "Python programming",
            id=f"test-search-{asyncio.get_event_loop().time()}",
            task_queue="test-duckduckgo-queue",
        )
        print(f"Success! Found {len(result)} results")


if __name__ == "__main__":
    asyncio.run(main())

Python, Pydantic AI & LLM client version

- Python 3.12
- pydantic-ai-slim[duckduckgo] >= 1.10.0
- ddgs >= 9.7.0