v1.101.0

pydantic/pydantic-aiv1.101.0May 22, 2026by DouweM

AI Summary

This release adds a pending message queue, MCP background task support, and model settings like `top_k`, alongside fixes for tool result dropping and thinking support.

Key Highlights

Added pending message queue (`ctx.enqueue` / `agent_run.enqueue`).
Added support for MCP background tasks (SEP-1686).
Added support for `top_k` model setting in Google, Anthropic, and Cohere models.
Fixed thinking support for Claude Sonnet 4.6 and Opus 4.6 on Bedrock.

New Features

Add pending message queue
Add support for MCP background tasks
Make `XSearch` capability model-agnostic
Support `top_k` model setting

Full Release Notes

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

## What's Changed
### 🚀 Features
* Add pending message queue (`ctx.enqueue` / `agent_run.enqueue`) by @DouweM in https://github.com/pydantic/pydantic-ai/pull/4980
* Add support for MCP background tasks (SEP-1686) by @Alex-Resch in https://github.com/pydantic/pydantic-ai/pull/5192
* Make `XSearch` capability model-agnostic via subagent fallback by @colesmcintosh in https://github.com/pydantic/pydantic-ai/pull/5120
* Support `top_k` model setting in `GoogleModel`, `AnthropicModel`, and `CohereModel` by @madanlalit in https://github.com/pydantic/pydantic-ai/pull/5558
### 🐛 Bug Fixes
* Fix `AnthropicModel` dropping code execution tool results when continuing a conversation by @2830500285 in https://github.com/pydantic/pydantic-ai/pull/5568
* Fix thinking being silently dropped for Claude Sonnet 4.6 and Opus 4.6 on Bedrock, and support adaptive thinking efforts by @sarth6 in https://github.com/pydantic/pydantic-ai/pull/5326
* Don't drop single `BaseModel` tool arguments sent in wrapped form when the model uses default `extra='ignore'` by @macayu17 in https://github.com/pydantic/pydantic-ai/pull/5560
* Preserve Xai tool result IDs and require `xai-sdk` 1.6.0 by @FU-max-boop in https://github.com/pydantic/pydantic-ai/pull/5355
### 📦 Dependencies
* Bump `genai-prices` minimum version by @adtyavrdhn in https://github.com/pydantic/pydantic-ai/pull/5565

## New Contributors
* @FU-max-boop made their first contribution in https://github.com/pydantic/pydantic-ai/pull/5355
* @putramkti made their first contribution in https://github.com/pydantic/pydantic-ai/pull/5559
* @2830500285 made their first contribution in https://github.com/pydantic/pydantic-ai/pull/5568
* @macayu17 made their first contribution in https://github.com/pydantic/pydantic-ai/pull/5560

**Full Changelog**: https://github.com/pydantic/pydantic-ai/compare/v1.100.0...v1.101.0