.NET: Support InvokeFunctionTool for declarative workflows#4014
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.NET: Support InvokeFunctionTool for declarative workflows#4014
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peibekwe
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Feb 17, 2026
peibekwe
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Feb 17, 2026
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Pull request overview
This PR implements support for the InvokeFunctionTool action in declarative workflows, enabling workflows to call functions directly without going through an AI agent first. This is a new capability that allows pre-fetching data or executing operations before AI involvement.
Changes:
- Adds
InvokeFunctionToolExecutorto execute function tool invocations in workflows - Implements workflow visitor pattern to integrate InvokeFunctionTool into the workflow execution model
- Includes comprehensive unit and integration tests
- Provides sample implementation demonstrating function tool invocation with and without approval requirements
- Updates package dependencies (Microsoft.Agents.ObjectModel from 2026.2.2.1 to 2026.2.3.1, PowerFx from 1.5.0 to 1.8.1)
Reviewed changes
Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/InvokeFunctionToolExecutor.cs | Core executor implementation handling function tool invocation, approval requests, result capture, and conversation integration |
| dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/WorkflowActionVisitor.cs | Visitor pattern integration to wire up InvokeFunctionTool in workflow execution graph |
| dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/WorkflowTemplateVisitor.cs | Marks InvokeFunctionTool as not supported in template workflows |
| dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/InvokeFunctionToolExecutorTest.cs | Unit tests covering executor functionality including approval, arguments, conversation ID handling |
| dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/InvokeFunctionToolWorkflowTest.cs | Integration tests validating end-to-end workflow execution with function tools |
| dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Workflows/InvokeFunctionTool.yaml | Test workflow demonstrating function tool invocation |
| dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Workflows/InvokeFunctionToolWithApproval.yaml | Test workflow demonstrating function tool invocation with approval requirement |
| dotnet/tests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Framework/WorkflowHarness.cs | Fixes checkpoint tracking and request counting for workflow resume operations |
| dotnet/samples/GettingStarted/Workflows/Declarative/InvokeFunctionTool/Program.cs | Sample program demonstrating InvokeFunctionTool usage |
| dotnet/samples/GettingStarted/Workflows/Declarative/InvokeFunctionTool/MenuPlugin.cs | Sample plugin with menu functions for demonstration |
| dotnet/samples/GettingStarted/Workflows/Declarative/InvokeFunctionTool/InvokeFunctionTool.yaml | Sample workflow YAML file |
| dotnet/samples/GettingStarted/Workflows/Declarative/InvokeFunctionTool/InvokeFunctionTool.csproj | Project configuration for sample |
| dotnet/agent-framework-dotnet.slnx | Adds new sample project to solution |
| dotnet/Directory.Packages.props | Updates package versions for ObjectModel and PowerFx dependencies |
dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/Interpreter/WorkflowActionVisitor.cs
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dotnet/src/Microsoft.Agents.AI.Workflows.Declarative/ObjectModel/InvokeFunctionToolExecutor.cs
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crickman
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Feb 17, 2026
...soft.Agents.AI.Workflows.Declarative.UnitTests/ObjectModel/InvokeFunctionToolExecutorTest.cs
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...ests/Microsoft.Agents.AI.Workflows.Declarative.IntegrationTests/Framework/WorkflowHarness.cs
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| ChatMessage requestMessage = new(ChatRole.Tool, [functionCall]); | ||
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| // If approval is required, add user input request content | ||
| if (requireApproval) |
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I wonder if approval and execution need to be separate turns?
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I thought about that, but I think it makes sense for the client to handle both however they see fit. We can get this in and get feedback from the service team and other users and change if needed.
alliscode
reviewed
Feb 18, 2026
| { | ||
| try | ||
| { | ||
| JsonDocument jsonDocument = JsonDocument.Parse(jsonString); |
Member
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Does this need to be disposed?
Suggested change
| JsonDocument jsonDocument = JsonDocument.Parse(jsonString); | |
| using JsonDocument jsonDocument = JsonDocument.Parse(jsonString); |
alliscode
reviewed
Feb 18, 2026
| await this.AssignAsync(this.Model.Output.Result?.Path, objectProperties.ToFormula(), context).ConfigureAwait(false); | ||
| return; | ||
| } | ||
| catch |
Member
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Can we narrow the catch to JsonException?
Suggested change
| catch | |
| catch (JsonException) |
alliscode
approved these changes
Feb 18, 2026
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Motivation and Context
This implementation supports the
InvokeFunctionToolaction in a declarative workflow to call functions directly from the workflow without going through an AI agent first. This is different from the standardInvokeAzureAgentpattern where the AI decides which functions to call based on the conversation.This PR includes tests and samples for the new action type and sample yaml implementations.
Fixes #3377
Fixes #3414
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