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Pull request overview
This PR fixes a critical bug in handoff orchestration where FunctionCall and Tool messages from handoff operations were being passed to target agents, causing the LLM to ignore the original user question. The fix filters out these internal workflow mechanics before sending messages to the target agent.
Changes:
- Added regression tests to verify that handoff function calls and tool results are not passed to target agents
- Added regression tests for multi-hop handoff scenarios to ensure proper message propagation
- Implemented FilterHandoffMessages method to remove handoff-related messages before sending to target agents
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| dotnet/tests/Microsoft.Agents.AI.Workflows.UnitTests/AgentWorkflowBuilderTests.cs | Added two comprehensive regression tests verifying that handoff targets do not receive handoff function messages in single and multi-hop scenarios |
| dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs | Added FilterHandoffMessages method to filter out handoff function calls and tool results; integrated filtering logic into the handoff message flow |
dotnet/src/Microsoft.Agents.AI.Workflows/Specialized/HandoffAgentExecutor.cs
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SergeyMenshykh
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Feb 10, 2026
westey-m
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Feb 10, 2026
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…agent (#3161) Filter out internal handoff function call and tool result messages before passing conversation history to the target agent's LLM. These messages confused the model into ignoring the original user question.
- Introduced HandoffToolCallFilteringBehavior enum to specify filtering behavior for tool call contents in handoff workflows. - Updated HandoffsWorkflowBuilder to support customizable handoff instructions and tool call filtering behavior. - Enhanced HandoffAgentExecutor to utilize new filtering options for improved message handling during agent handoffs.
…s and enhance filtering logic for non-handoff function calls
…tialization and improve clarity
…egration tests for handoff workflows
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This was referenced Feb 25, 2026
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Motivation and Context
The Handoff Orchestration currently does not filter out the HandoffTool FunctionCall messages or the Tool FunctionResult messages. This can cause odd behaviour, such as the LLM ignoring the original user question.
Description
FunctionCallandToolcontent (fixes .NET: [Bug]: Handoff orchestration does not pass message to the handoff agent #3161, .NET: [Workflows] Handoff tool response appears in chat history, causing inconsistent LLM behavior #3046)ChatMessagesbetween agentsContribution Checklist
Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.