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Python: [BREAKING] changed AIFunction to FunctionTool and @ai_function to @tool#3413

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eavanvalkenburg merged 12 commits into
microsoft:mainfrom
eavanvalkenburg:fix_2902
Jan 28, 2026
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Python: [BREAKING] changed AIFunction to FunctionTool and @ai_function to @tool#3413
eavanvalkenburg merged 12 commits into
microsoft:mainfrom
eavanvalkenburg:fix_2902

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@eavanvalkenburg

@eavanvalkenburg eavanvalkenburg commented Jan 23, 2026 •
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Motivation and Context

Updated naming of AIFunction to FunctionTool
Also added a default to the generic arguments
And the decorator from @ai_function to @tool
Fixes: #3247 and #3368
Closes: #2902 (final point has a additional issue created for it)

Description

Contribution Checklist

  • The code builds clean without any errors or warnings
  • The PR follows the Contribution Guidelines
  • All unit tests pass, and I have added new tests where possible
  • Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

Copilot AI review requested due to automatic review settings January 23, 2026 15:30
@markwallace-microsoft markwallace-microsoft added documentation Usage: [Issues, PRs], Target: documentation in the code base and learn docs python Usage: [Issues, PRs], Target: Python lab labels Jan 23, 2026
@markwallace-microsoft

markwallace-microsoft commented Jan 23, 2026 •
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Python Test Coverage

Python Test Coverage Report •
FileStmtsMissCoverMissing
packages/ag-ui/agent_framework_ag_ui
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   _utils.py101298%257, 262
packages/anthropic/agent_framework_anthropic
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packages/azure-ai/agent_framework_azure_ai
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packages/core/agent_framework/_workflows
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TOTAL16177241185% 

Python Unit Test Overview

Tests Skipped Failures Errors Time
3450 221 💤 0 ❌ 0 🔥 1m 6s ⏱️

Copilot AI reviewed Jan 23, 2026
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Pull request overview

This PR implements a breaking change that renames AIFunction to FunctionTool and the @ai_function decorator to @tool. The changes are comprehensive and consistent across the entire codebase.

Changes:

  • Renamed AIFunction class to FunctionTool throughout the codebase
  • Renamed @ai_function decorator to @tool
  • Updated serialization type identifier from "ai_function" to "function_tool"
  • Added default type parameters to the generic FunctionTool[ArgsT, ReturnT] using TypeVarWithDefaults
  • Fixed deepcopy issue with tools containing HTTP clients (addresses issue #3247)
  • Updated all samples, tests, documentation, and package code consistently

Reviewed changes

Copilot reviewed 108 out of 109 changed files in this pull request and generated 2 comments.

Show a summary per file
File Description
python/packages/core/agent_framework/_tools.py Core rename from AIFunction to FunctionTool, added TypeVar defaults, updated type identifier
python/packages/core/agent_framework/_agents.py Fixed deepcopy issue by shallow copying tools to avoid copying HTTP clients
python/packages/core/agent_framework/_types.py Updated normalize_tools and validate_tools functions, proper variable naming to avoid shadowing
python/packages/core/agent_framework/_serialization.py Updated documentation examples to use new naming
Various client implementations Updated all pattern matches and type checks across OpenAI, Azure, Anthropic, Bedrock, Ollama clients
Test files Comprehensive updates to all test files with consistent naming
Sample files All samples updated to use new @tool decorator and FunctionTool class
Documentation Updated README files and coding standards to reflect new naming
Comments suppressed due to low confidence (1)

python/packages/azure-ai/tests/test_provider.py:491

class MockMCPTool(MCPTool):  # pyright: ignore[reportGeneralTypeIssues]

Comment thread python/packages/core/agent_framework/_tools.py Outdated
Comment thread python/packages/ag-ui/agent_framework_ag_ui_examples/agents/ui_generator_agent.py Outdated
giles17
giles17 approved these changes Jan 24, 2026
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Believe this also fixes #3368

@giles17 giles17 mentioned this pull request Jan 24, 2026
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@droideronline

droideronline commented Jan 25, 2026 •
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@eavanvalkenburg @giles17 - Regarding #3368, the issue get resolved when instrumentation is disabled. I suspect
in _tools.py - self._invocation_duration_histogram = _default_histogram() to be the culprit.
when instrumentation is disabled, default histogram creates a No-op histogram but when Instrumentation is enabled, it create a histogram with Lock. Please have a look at this case as well. Thanks!

@TaoChenOSU

TaoChenOSU commented Jan 27, 2026

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Will this be accompanied by a documentation update PR?

@eavanvalkenburg eavanvalkenburg added this pull request to the merge queue Jan 27, 2026
github-merge-queue Bot pushed a commit that referenced this pull request Jan 27, 2026
@eavanvalkenburg
Python: [BREAKING] changed AIFunction to FunctionTool and @ai_functio…
487c63c 
…n to @tool (#3413)

* changed AIFunction to FunctionTool and @ai_function to @tool

* test and mypy fixes

* mypy fix

* switch function tool to always_require

* fix noop

* fix github copilot imports

* test fixes

* fix ollama test
@github-merge-queue github-merge-queue Bot removed this pull request from the merge queue due to failed status checks Jan 28, 2026
@eavanvalkenburg eavanvalkenburg added this pull request to the merge queue Jan 28, 2026
@github-merge-queue github-merge-queue Bot removed this pull request from the merge queue due to failed status checks Jan 28, 2026
@eavanvalkenburg eavanvalkenburg added this pull request to the merge queue Jan 28, 2026
@github-merge-queue github-merge-queue Bot removed this pull request from the merge queue due to failed status checks Jan 28, 2026
@eavanvalkenburg eavanvalkenburg added this pull request to the merge queue Jan 28, 2026
@github-merge-queue github-merge-queue Bot removed this pull request from the merge queue due to failed status checks Jan 28, 2026
@eavanvalkenburg eavanvalkenburg added this pull request to the merge queue Jan 28, 2026
Merged via the queue into microsoft:main with commit a7d924a Jan 28, 2026
35 checks passed
@HamidOna HamidOna mentioned this pull request Feb 14, 2026
Merged
This was referenced Apr 30, 2026
Closed
Closed
aishsawant0202-tech added a commit to aishsawant0202-tech/agent-framework that referenced this pull request May 4, 2026
@aishsawant0202-tech
docs: fix outdated @ai_function reference to @tool in workflows README
1e68da1 
The @ai_function decorator was renamed to @tool in release 
python-1.0.0b260128 (PR microsoft#3413) as a breaking change.

Line 58 of python/samples/03-workflows/README.md still referenced 
the old @ai_function name, causing users to hit:
ImportError: cannot import name 'AIFunction'

Changes made:
- Fixed @ai_function to @tool on line 58 only
- No formatting or whitespace changes
@aishsawant0202-tech aishsawant0202-tech mentioned this pull request May 4, 2026
Merged
github-merge-queue Bot pushed a commit that referenced this pull request May 4, 2026
@aishsawant0202-tech
docs: fix outdated @ai_function reference to @tool in workflows README (
e558d36 
#5622)

The @ai_function decorator was renamed to @tool in release 
python-1.0.0b260128 (PR #3413) as a breaking change.

Line 58 of python/samples/03-workflows/README.md still referenced 
the old @ai_function name, causing users to hit:
ImportError: cannot import name 'AIFunction'

Changes made:
- Fixed @ai_function to @tool on line 58 only
- No formatting or whitespace changes
@moonbox3 moonbox3 removed the lab label Jun 17, 2026
@eavanvalkenburg eavanvalkenburg deleted the fix_2902 branch June 30, 2026 09:02
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@TaoChenOSU TaoChenOSU TaoChenOSU approved these changes
@moonbox3 moonbox3 moonbox3 approved these changes
@giles17 giles17 giles17 approved these changes

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Python: [Bug]: Adding tools containing an HTTP client fails due to deepcopy in version 1.0.0b260114 Python: Review Agents API - Part 1 feedback

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