Set ToolRetryError message

[jamesaud]

Summary

ToolRetryError was not passing a message to Exception.__init__(), causing str(error) to return an empty string.

This came up when the agent loop crashes due to max tool retries, which breaks error monitoring tools like Sentry or Langsmith that rely on str(exception) to display and group errors.

Problem

from pydantic_ai.exceptions import ToolRetryError
from pydantic_ai.messages import RetryPromptPart

part = RetryPromptPart(content='Test error', tool_name='test')
error = ToolRetryError(part)

str(error)  # Returns '' (empty string)
error.args  # Returns ()

Solution

Pass tool_retry.model_response() to the parent Exception.__init__():

str(error)  # Now returns 'Test error\n\nFix the errors and try again.'

Changes

• pydantic_ai_slim/pydantic_ai/exceptions.py: Pass message to parent class
• tests/test_exceptions.py: Add ToolRetryError to hashable test + add dedicated string representation test

[DouweM]

Can we use tool_retry.content that contains just the error message, without the surrounding text instructing the model to retry?

Besides a str, content can also be a list of Pydantic error details, so we would need to stringify/dump those as to JSON.