Microsoft shipped dotnet-1.13.0 of the Agent Framework on July 3, 2026, bringing the Microsoft.Agents.AI NuGet package to version 1.13.0. This release focuses heavily on maturing the Skills API — graduating it from experimental to stable — along with meaningful Foundry Hosting improvements and new file editing capabilities.

For .NET developers building production agents and multi-agent systems on the Microsoft stack, this is a noteworthy maintenance release with enough new capability to warrant an upgrade review, though the breaking changes require attention before you update.

Skills API Goes Stable

The biggest conceptual change in 1.13.0 is the graduation of the Skills API from experimental status. What was previously marked [Experimental] is now considered stable GA API.

This matters because [Experimental] attributes in .NET carry real weight — IDEs and static analyzers warn you when you use them, and they’re considered fair game for breaking changes between releases. Removing that designation means the Microsoft Agent Framework team is committing to the Skills API as a stable interface.

The specific Skills API changes in 1.13.0 include:

  • AgentSkillsSourceContext support added to AgentSkillsSource.GetSkillsAsync — enabling richer context passing when loading skills
  • Skills source classes made public — previously only accessible through internal/experimental patterns
  • Consolidated skill-source caching — a performance and consistency improvement for agents that load skills at runtime
  • Skills sources now disposable — proper resource cleanup when skill sources are no longer needed
  • Skill approval options — new infrastructure for controlling which skills an agent is permitted to use

This last point — skill approval options — is interesting from an enterprise governance perspective. As agents gain access to more capabilities through skills, the ability to gate which skills are approved for use in specific deployments becomes a real compliance requirement for many organizations.

Foundry Hosting: Per-User Session Isolation

The Foundry Hosting improvements in 1.13.0 address a practical challenge for multi-tenant agent deployments: session isolation between users.

The new per-user session isolation ensures that agent state, memory, and context from one user’s session doesn’t leak into another user’s experience. This is table-stakes for production deployment but has historically required custom implementation — having it built into the framework reduces risk for teams deploying agents in enterprise environments.

Additional Foundry Hosting changes include:

  • Better support for local development (the framework now tolerates missing user identity in local runs, which was previously a friction point during development)
  • Responses v2 protocol support

New File Editing Tools + Breaking Changes

1.13.0 adds new file editing tools for agents — capabilities that allow agents to read, write, and modify files as part of their task execution. This expands the default tool surface for agents built on the framework.

However, these new tools come with breaking changes to the FileAccess and FileMemory store APIs. If your existing agents use these APIs, you’ll need to review the migration notes in the release changelog before upgrading.

The second breaking change affects the OpenAI Hosting OptionsMapping. This is a configuration-layer change — if you’ve customized OpenAI hosting options in your agent configuration, review the updated mapping structure.

Other Notable Changes

Beyond the headline features, 1.13.0 includes:

  • Dependency updates: Azure.AI.Projects and other Azure SDK dependencies bumped to current versions
  • Workflow fixes: Various fixes to agent workflow execution, particularly around approval and caching flows
  • Sample updates: The framework’s example projects updated to reflect new APIs and patterns
  • Richer approval/caching options: More granular control over when agents seek approval for actions and how results are cached

Migration Guidance

For teams upgrading from dotnet-1.12.x or earlier:

  1. Review the FileAccess/FileMemory API changes — if your agents use file operations, these are the highest-risk breaking changes
  2. Check OpenAI Hosting OptionsMapping — if you use the OpenAI hosting integration with custom options, verify your configuration against the new mapping structure
  3. Remove [Experimental] suppression attributes — any code that suppressed Skills API experimental warnings can now have those suppressions removed
  4. Test Foundry Hosting session behavior — if you deploy multi-user agents on Foundry, validate that the new session isolation behaves as expected for your use case

The full release notes are available at the GitHub releases page, and Microsoft.Agents.AI 1.13.0 is live on NuGet.

Context: The Bigger Microsoft Agents Picture

dotnet-1.13.0 is a maintenance release in the context of a much larger Microsoft agentic strategy. The Agent Framework is the production .NET library for building agents that integrate with Microsoft Foundry, Azure OpenAI, and the broader Microsoft 365 Copilot ecosystem.

The Skills API graduation is particularly significant in that broader context: skills are the modular capability units that let agents learn new capabilities without retraining. As this API matures, we’ll likely see a growing ecosystem of first- and third-party skills for the Microsoft agent ecosystem — similar to how extensions and plugins evolved for earlier Microsoft developer platforms.

For .NET enterprise developers building agents today, 1.13.0 is a solid, incremental step forward with some important stability commitments.

Sources

  1. GitHub Release — dotnet-1.13.0
  2. Microsoft.Agents.AI on NuGet
  3. microsoft/agent-framework — GitHub
  4. Microsoft Agent Framework Dev Blog

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