v1.64.0

pydantic/pydantic-aiv1.64.0Mar 2, 2026by DouweM

AI Summary

Adds an option to disable schema prompts and fixes various streaming, Google, MCP, and Anthropic issues.

Key Highlights

Support `template=False` on `PromptedOutput` and `NativeOutput` to disable schema prompt
Fixed Google streaming errors wrapping
Fixed MCP `__aexit__` race condition
Fixed Anthropic auto-fallback to streaming for high `max_tokens`

New Features

Option to disable schema prompts

Full Release Notes

<!-- Release notes generated using configuration in .github/release.yml at main -->

## What's Changed
### 🚀 Features
* feat: support `template=False` on `PromptedOutput` and `NativeOutput` to disable schema prompt by @DouweM in https://github.com/pydantic/pydantic-ai/pull/4497
### 🐛 Bug Fixes
* Fix missing `run_id` on `ModelRequest` in UI adapter runs by @madanlalit in https://github.com/pydantic/pydantic-ai/pull/4419
* Wrap Google streaming errors as `ModelHTTPError`/`ModelAPIError` by @saakshigupta2002 in https://github.com/pydantic/pydantic-ai/pull/4437
* fix(mcp): move `__aexit__` guard inside lock to prevent TOCTOU race by @jameslcowan in https://github.com/pydantic/pydantic-ai/pull/4435
* fix: `BaseToolCallPart.has_content()` incorrectly returns False for falsy arg values by @bsherifi in https://github.com/pydantic/pydantic-ai/pull/4442
* fix(anthropic): auto-fallback to streaming for high `max_tokens` by @DouweM in https://github.com/pydantic/pydantic-ai/pull/4496
* fix(vercel): Align `dump_messages` output with Vercel spec by @dsfaccini in https://github.com/pydantic/pydantic-ai/pull/4196
* fix: cancel sibling tasks on any exception in parallel tool execution by @LakshmiSravyaVedantham in https://github.com/pydantic/pydantic-ai/pull/4502

## New Contributors
* @jameslcowan made their first contribution in https://github.com/pydantic/pydantic-ai/pull/4435
* @bsherifi made their first contribution in https://github.com/pydantic/pydantic-ai/pull/4442
* @LakshmiSravyaVedantham made their first contribution in https://github.com/pydantic/pydantic-ai/pull/4502

**Full Changelog**: https://github.com/pydantic/pydantic-ai/compare/v1.63.0...v1.64.0