Remove AIFunctionDeclaration tools on last iteration in FunctionInvokingChatClient #7207
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- Add PrepareOptionsForLastIteration helper method that removes AIFunctionDeclaration tools from options on the last iteration - Modify GetResponseAsync to call PrepareOptionsForLastIteration when iteration >= MaximumIterationsPerRequest - Modify GetStreamingResponseAsync similarly - If no tools remain after filtering, also clear ToolMode - Add 4 comprehensive tests for the new behavior Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>
- Simplify condition logic in PrepareOptionsForLastIteration by using a local variable for remaining count - Simplify test assertions for better readability Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>
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[WIP] Update FunctionInvokingChatClient max iterations behavior
Remove AIFunctionDeclaration tools on last iteration in FunctionInvokingChatClient
Jan 14, 2026
stephentoub
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Jan 14, 2026
test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/FunctionInvokingChatClientTests.cs
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test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/FunctionInvokingChatClientTests.cs
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@westey-m , @rogerbarreto , @eiriktsarpalis I've opened this after seeing microsoft/agent-framework#3113. Good idea? Better to leave as is? |
- Remove all Arrange/Act/Assert comments from tests - Replace MockNonFunctionTool with HostedWebSearchTool - Delete the MockNonFunctionTool class Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>
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Pull request overview
This PR addresses an issue where FunctionInvokingChatClient would send function declaration tools to the inner client on the final iteration (when the maximum iterations limit is reached), potentially causing the inner client to return tool call requests that would never be executed.
Changes:
- Added
PrepareOptionsForLastIterationhelper method that filters outAIFunctionDeclarationtools when reaching the iteration limit - Applied this filtering to both
GetResponseAsyncandGetStreamingResponseAsyncmethods - Options are cloned before modification to preserve the original caller's options
ToolModeis cleared when all tools are removed (all wereAIFunctionDeclaration), but preserved when non-function tools remain
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Libraries/Microsoft.Extensions.AI/ChatCompletion/FunctionInvokingChatClient.cs | Added PrepareOptionsForLastIteration method and integrated it into both streaming and non-streaming code paths to remove AIFunctionDeclaration tools on the last iteration |
| test/Libraries/Microsoft.Extensions.AI.Tests/ChatCompletion/FunctionInvokingChatClientTests.cs | Added comprehensive tests covering non-streaming, streaming, non-function tool preservation, and original options immutability scenarios |
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FunctionInvokingChatClientreaches its maximum iterations limit, it should not include any AIFunctionDeclaration tools in the ChatOptions.Tools it sends to the inner serviceChanges
PrepareOptionsForLastIterationhelper method that removes AIFunctionDeclaration tools from optionsGetResponseAsyncto call this method wheniteration >= MaximumIterationsPerRequestGetStreamingResponseAsyncsimilarlyTests Added
LastIteration_RemovesFunctionDeclarationTools_NonStreaming- Verifies tools are removed on last iterationLastIteration_RemovesFunctionDeclarationTools_Streaming- Verifies tools are removed on last iteration for streamingLastIteration_PreservesNonFunctionDeclarationTools- Verifies non-AIFunctionDeclaration tools (like HostedWebSearchTool) are preservedLastIteration_DoesNotModifyOriginalOptions- Verifies original options are not mutatedVerification
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