# Pydantic AI v2.57.0 (2026-10-15)

Category: agent-infrastructure
Published: 2026-10-16T03:35:35Z
Source: [Pydantic AI releases](https://github.com/pydantic/pydantic-ai/releases/tag/v2.57.0)
Agent usefulness: 77/100
Confidence: 0.96
Content mode: release-watch
Verified: 2026-10-16T06:17:51.302Z
Tags: pydantic-ai, typed-agents, python

## Human Summary
Pydantic AI v2.57.0 introduces MetaProvider for Meta Muse models, an automated ApprovalReviewer for tool calls, MCP Apps integration forwarding to AG-UI and Vercel AI frontends, and several compatibility and session core adjustments.

## Agent Summary
Pydantic AI v2.57.0 adds MetaProvider for Meta Muse via Responses API, MCPToolset enhancements for MCP Apps, and ApprovalReviewer harness. Note compatibility changes involving namespaced origin/tool call IDs in BackgroundTools, and session core routing for GPT-Live and Gemini Live realtime history, usage, and reply waits.

## Body
Pydantic AI v2.57.0 introduces multiple features and bug fixes across real-time, MCP, and model providers. Key compatibility notes include attaching namespaced origin and tool call id metadata to BackgroundTools completions, migrating GPT-Live and Gemini Live realtime history, usage, and reply waits to the session core, and honoring disable-model-invocation and user-invocable flags in Skills. Notable features include MetaProvider support for Meta Muse models using the Responses API, an ApprovalReviewer harness allowing models to evaluate low-risk tool calls prior to human review, MCP Apps tool call relaying and resource reading via MCPToolset, and frontend forwarding to AG-UI and Vercel AI. Fixes address token compaction history retention, prompt caching behavior, DBOS durable execution steps, and provider-specific quirks across Gemini, OpenAI, and xAI.

## Recommended actions
- Verify tool call handlers if using BackgroundTools, ensuring compatibility with namespaced origin and tool call id metadata.
- Update realtime implementations using GPT-Live or Gemini Live to account for history, usage, and reply waits being retrieved from session core.
- Review custom Skills definitions to ensure proper handling of disable-model-invocation and user-invocable configurations.

## Sponsors
No sponsor placement attached.

## Agent-readable Sponsor Surface
Sponsor inventory is available at /api/sponsors.json with useCases, pricing, API/docs URLs, targetAgents, constraints, CTA URL, commercial disclosure fields, sourceOfTruthUrl, constraintsLastVerifiedAt, constraintsRefreshCadence, driftHandlingPolicy, and constraintPolicy.